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Annales Societatis Geologorum Poloniae (2020), vol. 90: 513–534 doi: https://doi.org/10.14241/asgp.2020.34
In describing the processes of formation and the forms of
lava caves, researchers are in an exceptionally favourable
position. The formation of lava tubes, especially at an early
stage, has been well described from contemporary volca-
noes, for example in Hawaii (Fig. 1) and on Mount Etna.
Lava tubes, dened by Halliday (2004) as a “roofed conduit
of owing lava, either active, drained, or plugged”, are com-
mon volcanic features with tunnel-like appearances. They
are natural conduits, through which lava travels beneath
the surface of a lava ow. When the supply of lava stops at
the end of an eruption or the lava is diverted elsewhere, lava
in the tube system typically drains downslope and leaves
partially empty conduits beneath the ground. However, al-
most all the accessible lava caves have undergone moderate
to substantial downward erosion. Thus, the lava conduit may
leave an accessible cave without draining (S. Kempe, pers.
comm., 2020). Recent overviews of problems, related to the
description, genesis, nomenclature, etc. of lava caves, were
presented by Halliday (2002) and Kempe (2012b, 2019).
Lava tubes (pyroducts) form in volcanic ows and are
found in many volcanic regions of the world, for example,
in the USA (Kilauea Volcano in Hawaii; Kauahikaua et al.,
1998), Italy (Mount Etna; Calvari and Pinkerton, 1998),
Australia (Undara Volcano; Atkinson et al., 1975), Iceland,
the Canary Islands, Azores, India, Vietnam, Korea, Japan,
Galapagos Islands, Easter Island, Mexico, Kenya, Saudi
Arabia and Jordan (Sauro et al., 2020 and references there-
in). Lava tubes are well known to people, who live in the
areas where they are common, but poorly known in Europe,
except perhaps in Iceland and Italy. They are the subject of
volcanospeleologic research, a term coined by William R.
Halliday (Kempe, 2012a). Various terms are used for the
primary forms: lava tubes, lava pipes, lava tunnels, or py-
roducts. A crust forms on the surface of the cooling lava
above the conduit. The prime difference between “channel”
and “tube” is that the crust on the channel is discontinu-
ous and moving in downstream direction, while the crust
over the tube is stationary (e.g., Keszthelyi et al., 1999).
An open lava channel can evolve into a lava tube and it
is not always easy to distinguish between a lava tube and
a lava channel (e.g., Duraswaimi et al., 2004). Accordingly,
some researchers have used the term “canals/pipes” (see
Sen et al., 2012 for discussion). Although the term “lava
tube” is used most often nowadays, it is worth noting
the development of these terms in the geological literature,
as summarized in table 6.2 of Lockwood and Hazlett (2010).
These authors, also Kempe (2012b, 2019), strongly advise
the use of the term “pyroduct” – “any internal lava conduit
in a ow, irrespective of shape and size, regardless of wheth-
er it contains molten lava during eruptive activity or is pre-
served as an elongate cave after eruptive activity ends and
molten rock drains away”. There are two reasons for this.
One is that the older term should take precedence. The term
“pyroduct” was coined already in 1844 by the Reverend
Titus Coan, after seeing a pyroduct in action on Mauna Loa,
in March 1843 (Coan, 1844 de Lockwood and Hazlett,
A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
Zbigniew SAWŁOWICZ
Jagiellonian University, Faculty of Geography and Geology,
Institute of Geological Sciences,
Gronostajowa 3a; 30-387 Kraków, Poland;
e-mail: zbigniew.sawlowicz@uj.edu.pl
Sawłowicz, Z., 2020. A short review of pyroducts (lava tubes). Annales Societatis Geologorum Poloniae, 90:
513 – 534.
Abstract: Lava tubes and caves, when accessible for man, are very common in volcanic environments and poorly
known to non-specialists. This short overview presents the distribution and forms of lava tubes, their speleothems
and mineralogy and modes of formation. Studies of lava caves outside of Earth currently are a topic of great
interest, as they may be potential locations for some life forms and future bases in space exploration. Basic features
of lava tubes are illustrated with reference to the longest lava cave in the world, Kazumura Cave, in Hawaii.
Key words: caves, speleothems, extraterrestrial, volcanic environment, Kazumura Cave.
Manuscript received 19 October 2020, accepted 22 March 2021
INTRODUCTION
514 Z. SAWŁOWICZ
2010). The term “lava tube” was used later, for the rst time
by Tom Jaggar in 1919 (Jaggar, 1919 de Lockwood and
Hazlett, 2010). This term creates the impression of a tubular
passage that can carry lava under pressure, which typically
is not the case. Most passages are rectangular and the roof of
a pyroduct does not have the tensile strength to sustain the
pressure on owing lava, apart from its own weight. Thus,
the term “pyroduct”, as dened above, seems to be more
appropriate and should be used preferentially. In saying
this, the present author cannot negate the terminology that
is rooted in the extensive literature on the subject and will
use different terms interchangeably herein.
Some authors (e.g., Gradziński and Jach, 2001) distin-
guish between a lava tube and a lava cave, the latter being
accessible to humans. Some researchers describe lava caves
as “pseudokarst” but this term does not seem to be appropri-
ate (see discussion in Eberhard and Sharples, 2013).
Lava caves are quite common in the volcanic environ-
ments but poorly known to the public, including many spe-
leologists. They pose a challenge to the standard thinking
of a geologist because, unlike karst caves, they form in
a geological instant, from a few weeks to a few years.
In this short overview the author would like to show why
lava caves are of great potential importance, describing:
1) the environment and modes of formation; and 2) the
differences and similarities between lava and karst caves.
Kazumura Cave (Big Island, Hawaii), the longest lava cave
in the world, is presented here as providing excellent and
representative examples of various lava features.
GENERAL CHARACTERISTICS
OF LAVA TUBES
Distribution and forms
Volcanic caves are a broad group, which includes the
caves created by volcanic explosion, lava effusion and var-
ious volcanic processes. Bella and Gaál (2013, and refer-
ences therein) distinguished roofed lava channels, lava tube
caves, drainage tubes of active rift zones, lava rise caves,
lava ridge caves, lava tumulus caves, boulder caves in lava
ows, volcanic crater shafts, volcanic exhalation caves,
chimneys of spatter cones and hornitos, lava blister caves,
polygenetic spatter cone caves in carbonatite volcanoes,
volcanic pyrogenetic tree moulds, and volcanic eruptive s-
sure caves. By far the most common are the rst two types.
Most of the pyroducts that actively transmit lava in a subter-
ranean setting formed syngenetically with the laterally ow-
ing lava: they are described in detail below. Lava tubes and
channels occur also in seaoor volcanic terrains of the East
Pacic rise and in seamounts in the eastern Pacic. They
can form horizontal intracrustal pathways for the circulation
Fig. 1. Surface expressions of volcano and lava tubes. A. Kilauea Iki crater and fumes of the Halema ̒uma ̒u crater (active vent)
of the Kilauea caldera in the backround. B. Upwarped lava sheets detached from their sheet below owing to lateral pressure. C. Large
collapse giving horizontal access to cave passage. D. Collapse (puka) above large cave.
515A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
of hydrothermal uids (Fornari, 1986). Secondary caves in
lava ows often are formed along tectonic ssures as a re-
sult of the collapse of the ceilings of igneous chamber frag-
ments and by erosion (the shorelines of the seas and lakes or
the banks of rivers; Kempe, 2012a, and references therein).
It is worth noting, however, that distinguishing the origins
of some caves is not easy. For example, one cave (Kuka ̒au
Cave) in the Hamakua volcanites on Mouna Kea, was
formed as a result of erosion (Kempe and Werner, 2003),
while the other (P ̒a ̒auhau), was established originally as
a lava tube, but was later modied as a result of erosion
by a stream (Kempe et al., 2003).
Almost all caves are formed in alkaline and tholeiitic ba-
salt; among the few exceptions are caves formed in phono-
lites and carbonatites (McFarlane et al., 2004; Kempe, 2013
and references therein). Two main types of lava host the
majority of lava caves and channels: a ̒a (rough, brecciated
basalt lava) and pāhoehoe (Fig. 2; smooth, glassy basalt lava;
Hawaiian nomenclature; Harris et al., 2017). Channels are
commonly found in both a ̒a and pāhoehoe ows, whereas
Fig. 2. Various types of Hawaiian basalt lavas (Big Island). A. Pāhoehoe lava on the coast. Note a pressure-ridge in the backround with
possible cave underneath. B. Undulating surface of the frozen tongue of ropy pāhoehoe lava. C. Pāhoehoe lava ow. D. Cross-section of
a pāhoehoe ow exposed in a sea cliff. Different colours of the individual ow units resemble those observed in lava tubes. E. Sequence
of ows: older pāhoehoe (op) – pāhoehoe (p) – younger ̒ ̒a (ya). F. A ̒a ow (darker) over older pāhoehoe ow (shiny).
516 Z. SAWŁOWICZ
tubes are much more common in pāhoehoe ows (e.g., Hon et
al., 1994; Kauahikaua et al., 2003). However, more and more
evidence is emerging that the lava tubes in a ̒a ows are not
as rare as previously was thought (e.g., Coombs et al., 1995;
Calvari and Pinkerton, 1999; Wantim et al., 2013). A ̒a lava is
found on the oors of lava caves as a result of terminal cool-
ing that increases the viscosity of the lava, pulling the lava
apart to form clinker (S. Kempe, pers. comm., 2020). There
are several other rarer lava tubes. Discrete lava tubes form in
hummocky ows, in which lava pathways have many dead
ends, so that the lava cannot ow (Wise, 2014). Special “litto-
ral” tubes associated with pillows, rarely drained and mostly
plugged, form when the lava ow reaches the sea (Peterson
et al., 1994). Lava tumuli can be hollow inside (e.g., in
Kilauea caldera; Halliday, 1998). Pedersen et al. (2017) de-
scribed tumuli hosting small caves and chambers, associated
both with a ̒a and pāhoehoe inationary tubes, which result-
ed from lava being injected from below. Deep “inated-en-
trenched” lava tubes, some being very large, were considered
to be formed through ination along deep inception horizons,
following previous lava ow boundaries. There, after ina-
tion, the conduit is enlarged by downward, thermic erosion
and breakdown phenomena (see Kempe, 2019). Channel
curvature affects the surface morphology and dynamics of
the ow and can stimulate the formation of a lava tube
(Valerio et al., 2011).
Lava tubes/pyroducts may be divided into single-trunk-
ed, double (or multiple)-trunked, and superimposed-trunk-
ed systems (Kempe, 2009). Lava channels and tubes often
form distinctly complex networks with anastomosing and
braided reaches. They often intersect or join in different
lava ows (Kempe, 1999). Examples of various systems
can be found in Kempe (2013). Such systems can greatly
inuence the development of the coastline in volcanic areas
(e.g., Kauahikaua et al., 1993; Umino et al., 2006; Ramalho
et al., 2013).
The formation of lava tubes is a relatively fast process.
Their growth is hampered by the rate of lava cooling and
local topography. It also is inuenced by changes of inter-
nal pressurization, associated with the ination of a lava
ow (Glaze and Baloga, 2015). The population density of
the tubes is inversely proportional to their diameter (Coombs
et al., 1995). Sustained ow forms small tubes over pe-
riods of hours to days (e.g., Peterson et al., 1994; Byrnes
and Crown, 2001), whereas large tubes form over weeks
to months (e.g., Harris et al., 1997; Calvari and Pinkerton,
1998). Kempe et al. (2018) pointed out that, contrary to
popular opinion, lava caves are not created at the end of the
eruption “when the tube runs empty”, but prolonged activity
creates a gas space above the down-cutting lava river.
Most of the intact lava tubes are restricted to lavas that
are less than a few million years old. Among that old-
est are the San Antonio Mountain Cave (SAM) in New
Mexico (nearly 4 Ma, Rogers et al., 2000) and lava caves of
the Al-Shaam plateau in Jordan (about 7 Ma; Kempe and
Al-Malabeh, 2005). Tubes in older volcanic environments
typically collapse, forming rills, sinuous ridges and chan-
nels, and/or are lled with sediments.
Lava tubes start typically at the shield volcano that is-
sued the lava. For example, tubes, as much as 20 m high
and 10–25 m wide, were observed within a kilometre of the
Pu’u ‘O’o-Kupaianah eruption of Kilauea (Kauahikaua et al.,
1998) or at a distance of 600 m from a vent at the Mount
Cameroon Volcano (Wantim et al., 2013). The distance and
the length are dependent on many factors, such as morpholo-
gy, volume, channel width, viscosity of lava, etc. The lengths
of lava caves vary from a few metres up to tens of kilometres
and their width and height vary from about 0.2–0.5 m up to
30 m (Bunnell, 2008), but it should be noted that locally the
dimensions of lava caves do not correspond to primary py-
roducts, owing to, for example, erosion. The depth below the
surface ranges from a few centimetres to a depth of a few tens
of metres, typically less than 10–20 m (the total depth of lava
caves is described as the difference between maximum and
minimum altitudes above sea level). In most cases, tubes are
sub-parallel to the surface itself.
Various factors are important in the internal development
of the pyroducts, such as the joining of the smaller ducts,
expansion during ination, and thermal erosion of the sub-
strate (Coombs et al., 1995). During lava ow, tubes can be
lled completely or only partly. Typically, the lava level in
the conduit decreases, as a result of either reduced lava sup-
ply, or enlargement of the corridor cross-section due to ero-
sion, with constant lava ow (e.g., Kauahikaua et al., 1998).
The shape of the tube can be very complex and varied (see
for example Calvari and Pinkerton, 1999). They can con-
tinue to evolve in dimensions and shape, from an elliptical
cross-section to arched, round, oval, or alternatively keyhole
shaped, owing to the formation and failure of blockages,
changes in effusion rate, thermal and mechanical erosion,
or slope changes (e.g., Kauahikaua et al., 1998; Kerr, 2001;
Dragoni and Santini, 2007; Diniega et al., 2013). Bends in
a lava ow are often observed, and these can strongly affect
the ow dynamics and the formation of lava tubes (Greeley,
1971; Peterson et al., 1994). Common lava features in
caves are lava stalactites, stalagmites, helictites, columns,
owstone, coralloids, grooves (ow lines), shelves, ceiling
cusps, linings, lava falls, dams, levees, gutters and benches
(e.g., Larson, 1993). The tube walls exhibit a single layer
of lava lining at some places, whereas elsewhere it shows
additional layer (e.g., Duraswaimi et al., 2004; McHale,
2013; Fig. 3). Subsequent linings of the lava tube can have
Fig. 3. Simplied cross-section through a lava tube, with lining,
levee and most common types of lava speleothems (after Onac and
Forti, 2011, modied).
517A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
different colours and compositions, depending on the pri-
mary composition and/or oxidation processes in the lava
tube. Lava also can change its composition, owing to melt-
ing and the incorporation of the bedrock.
Research by Williams et al. (2003) in Cave Basalt (Mount
St. Helens) has shown that the oldest outer lava linings in
direct contact with dacite substrates are contaminated with
substrate material, while younger, internal lava linings are
uncontaminated. Contraction cracks, observed in the roof,
are occasionally lled with sediments (Waichel et al., 2013).
In active volcanic elds, tubes typically do not leave much
surface expression, but occasionally tubes are marked by
features, such as hornitos, elongate tumuli, skylights and
break-outs (Fig. 1; Hon et al., 1994; Calveri and Pinkerton,
1998; Kauahikaua et al., 2003). Various holes/skylights are
especially common above lava tubes and often used in ex-
ploration for them. They are called “pukas” in Hawai‘i or
“jameos” in the Canary archipelagos and usually form sin-
uous chains (Sauro et al., 2020). Skylights usually result
from collapse of the roof, which can be due to gravitation-
al effects or ow overpressure (e.g., Cushing et al., 2015;
Sauro et al., 2020) or through incomplete crusting over
a lava channel developing into a lava tube. Kempe (2012a)
distinguished two types of collapse forms: 1) a “hot
puka”, when the lava ow is still active and the rubble
is carried away; and 2) a “cold puka”, formed after the
ow terminated and breakdown remains. Hot pukas cool
the lava inside the tube and allow observations of the hot
lava owing under the surface. The temperature difference
between the core of the lava stream and its surface can
range from 29 to 144 °C (Witter and Harris, 2007). These
primary skylights are very important in the formation of
lava ows, changing air ow (cooling) or redirecting a
lava ow. For example, Kempe (2012a) observed the col-
lapse of the primary ceiling (hot puka), which allowed the
inow of cold air and consequently the solidication of
the lava stream surface and the formation of a secondary
ceiling. When lava is ejected through an opening in the
lava crust, conical structures, hornitos, form. Lava can also
invade a cave through cold pukas, forming a variety of
large, vertical ow features (Kempe, 2013), for example,
lava falls and lava curtains that fall into pre-existing pu-
kas. Occasionally a ̒a ows over older ows (see Fig. 2E,
F) and enters pre-existing tubes through skylights or col-
lapsed lava tubes (Shervais et al., 2005), locally blocking
them. Secondary skylights can form later, owing to tecton-
ics or erosion.
The signicance of lava tubes in volcanic ows is dif-
cult to overestimate. Shield volcanoes owe their shape
to the fact that low-viscosity, high-temperature lavas
form internal tunnels, in which the lava can be trans-
ported for tens of kilometres (Kempe, 2009). The spe-
cic morphology of shield basalt volcanoes is largely
due to the presence of numerous lava tubes that evenly
and over long distances distribute the discharged lava
(e.g., Peterson et al., 1994). Within many lava ows
in Hawaii, for example, lava tubes regularly facilitate
transport of basaltic lava over distances of 10–20 km
with temperature drops of ≤1 °C/km (Kauahikaua et al.,
2003). Lava tubes are important in the development
of lava ow areas, both pāhoehoe (e.g., Peterson and
Tilling, 1980), and a ̒a (e.g., Calvari and Pinkerton, 1999),
enabling the formation of longer and wider lava ows
(e.g., Cashman et al., 1998; Al-Malabeh and Kempe,
2012). They facilitate the swelling/ination of pāhoehoe
ows (Hon et al., 1994; Pasquarè et al., 2008). Lava ows
not only use previously formed lava tubes but can also
destroy them.
Thermal and mechanical erosion
One of the important mechanisms for the formation of
lava channels and pyroducts is thermal and/or mechanical
erosion by owing lava (e.g., Kauahikaua et al., 1998).
It involves some combination of thermal melting and as-
similation and/or mechanical plucking and entrainment of
underlying substrates by hot owing lava (Hulme, 1973;
Huppert et al., 1984; Williams et al., 1998). In the case of
loose rubble, for example of a ̒a lava, simple, mechanical
erosion can be a major force (Kempe, 2012b). The distinc-
tion between thermal and mechanical erosion is difcult and
often problematic, especially that often both processes are
very effective and responsible for the nal result. Gallant
et al. (2020) documented extreme thermo-mechani-
cal erosion by a small volume of lava. Downcutting by
a basaltic-andesitic lava ow on the volcano Motombo
(Nicaragua) was a hundred times the rate reported for ther-
mal erosion in lava ow elds.
Generally, thermal erosion is more effective: in consol-
idated, non-volcanic substrates, having a lower melting
temperature than lava, low mechanical strength, higher
volatile content and lower conductivity; at lower slopes; at
lower gravity; with a prolonged period of ow and higher
turbulence (Hulme, 1982; Greeley et al., 1998; Kerr, 2009;
Hurwitz et al., 2010). The efciency of thermal erosion
depends also on the physical properties of magma,
which depend to a major extent on magma composition
(Whittington et al., 2020 and references therein). Thermal
erosion channels in lavas have been identied, for ex-
ample, in Hawaiian basaltic ows (Kauahikaua et al.,
1998), in low-viscosity and low-temperature carbonatite
lava (Kerr, 2001), and in Archaean komatiite lava ows
(Williams et al., 1999). Coombs et al. (1995) calculated
the thermal erosion rate of lava ows and tubes on Kilauea
at 5.4 cm per day for 74 days.
Mechanical erosion is more effective in unconsolidat-
ed substrates (e.g., regolith; Hurwitz et al., 2010). Siewert
and Ferlito (2008) developed a model for mechanical ero-
sion that explains the main eld observations. Williams
et al. (2003) found a greater abundance of xenoliths and
xenocrysts relative to xenomelts in the Cave Basalt (Mt. St.
Helens, USA) and suggested that mechanical erosion rather
than thermal erosion was the dominant, erosional process.
It seems reasonable to use the term “mechanical/thermal
erosion” in all questionable cases. It is also important to bear
in mind the fact that in the processes of channel and tube
formation, erosion is not the only possibility. For example,
caves in a carbonatite volcano in Tanzania were formed by
thermal erosion and the aqueous dissolution of spatter cones
(McFarlane et al., 2004).
518 Z. SAWŁOWICZ
Temperature, viscosity and lava ow rate
in an active lava tube
Lava tubes can be excellent insulators of a lava ow.
Isolating the lava in the tube reduces its rate of cooling
and thus increases its range of ow (e.g., Keszthelyi, 1995;
Keszthelyi and Self, 1998). The maximum surface tem-
perature of the lava runoff in a Kilauea tube was 1,138 °C,
and 1,020 °C at the outow from the tube (Pinkerton et
al., 2002). The transport through lava tubes over 100 km
in length of lava in inated ows permits the molten lava
core to reach the ow front, with a cooling rate of less than
0.5 °C/km (e.g., Keszthelyi, 1995; Sakimoto and Zuber,
1998; Riker et al., 2009). The effective insulation provided
by the roof means that tube-fed ow has the potential to
extend tens to hundreds of kilometres before the core cools
by 200 °C, in spite of low (1–4 m3/s) effusion rates (Harris,
2006). In a master tube with a thick roof, the cooling rate
is the lowest among all types of lava ow. Length of lava
ow, assuming that composition, isolation and morpholo-
gy are constant, will rise with the effusion rate (Harris and
Rowland, 2009). The heat loss of the magma in the lava tube
is different than that in the surface runoff. The studies of
Pinkerton et al. (2002) of Kilauea ows and tubes showed
that tubed ows have a different surface thermal prole com-
pared to those of active channels in subaerial ows. Tubed
ows have margins that are cooler than the centres (see also
Flynn and Mouginis-Mark, 1994); this reects the increased
importance of conductive heat loss through the tube walls,
compared to radiant heat loss from the surface. Detection
of thermal anomalies can help to locate the positions of ac-
tive lava tubes, Temperature distributions on pāhoehoe ow
elds revealed temperature anomalies of up to 150 °C above
active tubes and tumuli (Pinkerton et al., 2002).
The rate of lava ow in a tube and its width and height
can be determined, among other properties, by measuring
its ow between two skylights (Tilling and Peterson, 1993).
The velocities of lava ows measured within channels and
tubes are typically 1–3 m/s but may approach as much as 10
m/s (e.g., Hon et al., 1994; Kauahikaua et al., 2003; Harris
et al., 2007). Changes in velocity and viscosity of lava ows
lead to the formation of different lava types. Belousov and
Belousova (2018) studied different types of lava ows of
the 2012–2013 eruption of the Tolbachik volcano. They
showed signicant differences in the propagation velocities
of ows and the viscosity of a ̒a and pāhoehoe (velocity 2
to 25 mm/s and 0.5 to 6 mm/s and viscosities 1.3×105 to
3.3×107 Pa.s and 5×103 to 5×104 Pa.s, respectively). The pa-
rental lava was identical for both lava types. The viscosity
of lava runoff generally increases with time, as the cool-
ing effect becomes important. Diniega et al. (2013) studied
the inuence of viscosity on lava ow dynamics and creat-
ed a model that presented a plausible explanation for why
channels and tubes are common features of basaltic ows.
Modelling of the lava ow in the tubes shows that pres-
sure is the determining factor for very slight slopes, while
for higher slopes, gravity becomes the determining factor
(Sakimoto et al., 1997).
Lava tube mapping methods
and lava temperature assessment
Most lava tube mapping to date on Earth has been done
directly by humans. There is a growing interest in use of
sophisticated instrumental, mainly geophysical, methods.
Location of the lava ows, channels and tubes has been
studied by means of several techniques, e.g., geoelectro-
magnetic (Bozzo et al., 1994), changes in the magnetic eld
(Budetta and Del Negro, 1995), radar (GPR; Miyamoto
et al., 2005), laser scanning (TLS – 3D models; Nelson et
al., 2011), very low frequency electromagnetic induction
(VLF; Kauahikaua et al., 1990), Forward Looking InfraRed
(FLIR) thermal camera (Spampinato et al., 2008), multi-
spectral infrared images, tracing a 10–15 o C temperature
anomaly on the surface, directly above the tube (TIMS;
Realmuto et al., 1992), and estimation of lava ow tem-
peratures, using Landsat night-time images (Nádudvari
et al., 2020).
Several geophysical methods were used beyond the Earth.
For example: on the Moon (NASA’s GRAIL mission –
Chappaz et al., 2014) and on Mars (images of THEMIS,
MOC and HiRISE – Giacomini et al., 2009; VNIR and
TIR – Crown and Ramsey, 2017; Helmholz resonance –
Williams et al., 2017). Various technologies for robotic ex-
peditions that will explore skylights, lava tubes and caves
on other planets and moons have been proposed (Antol,
2005; Whittaker, 2011; Kalita et al., 2018).
Formation of pyroducts (lava tubes)
The formation of pyroducts may be a very complex
and multi-stage process, involving several lava ows (see
e.g., Bauer et al., 2013). The rst, genetic observations of
actively forming lava tubes by “overcrusting” of an open
channel were made by Peterson and Swanson (1974) during
long-lasting effusive eruptions at the Kīlauea volcano, on
the Island of Hawaii. Excellent reviews of various forma-
tion processes can be found in Kempe (2012a, 2019) and
more recently in Sauro et al. (2020).
Several modes of formation of lava tubes (pyroducts)
exist (Fig. 4). Two main ways (Kempe et al., 2010) are:
1) “Inationary” (Fig. 4A) – The lava ows grow at their
distal tips, where hot lava quickly covers the ground in thin
sheets. The next advance makes this sheet swell before the
formation of the next distal surface sheet and later down-
ward erosion. This process can be repeated. 2) “Crusting
over of channels” by closure by slab jam and closure by
lateral shelf growth (Fig. 4C left and right, respectively).
The tubes that form by roong over the channels tend to
have relatively thin roofs (roof thickness << tube diameter),
whereas the tubes that form within inated sheets tend to
have thicker roofs (Keszthelyi et al., 1999). Most pyrod-
ucts form by the rst process at the tip of the lava ow by
a repeated process of advance and ination (Kempe, 2013).
Those interested in the differences between “inationary”
versus “crusted-over roofs of pyroducts” are directed to
Kempe et al. (2010).
519A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
Kempe (2012a) distinguished also caves, formed by coa-
lescence of small ducts and consecutive downward erosion
(Fig. 4B). During long-lasting eruptions, several small tubes
can merge focusing the ow along one main path. The fo-
cused ow has stronger thermal erosion potential and can
enlarge and entrench the conduit (Kempe, 2019). Bauer
et al. (2013) described the Kahuenaha Nui Cave (Hawaii),
which formed in four different lava ows. First, the trunk
passage formed by eroding an underlying a ̒a rubble layer.
Then, a stack of several superimposed pāhoehoe ows with
small ducts combined into one ow, eroding the main trunk
underneath.
Lava tubes, formed by shallow ination, usually are
characterized by a surcial bulge (due to ination) and by
an original horizontal elliptical cross-section that can be
entrenched by thermal erosion (Sauro et al., 2020). The de-
velopment of tunnels that carried lava to the distal fronts
due to the reduction in effusion rates may generate localized
ination phenomena throughout the lava ow (Bernardi
et al., 2019).
Crusting over the channel can happen through different
mechanisms, operating separately or in combinations , de-
pending on the ow rate, turbulence and channel geometry
(Dragoni et al., 1995; Sauro et al., 2020): 1) the growth of
solidied, rooted crusts from lava stream banks; 2) over-
ows and spatters, accreted to form shelves and levees that
progressively grow, forming a roof across the stream; and 3)
plates and lithoclasts of solidied lava oating downstream,
welding together and forming a blocky roof. Overcrusted
tubes are usually limited to the width and depth of the
Fig. 4. Different cave formation modes within the pyrodct. A. Ination of the lava ow front and later downward erosion. B. Coalescence
of small ducts and consecutive downward erosion. C. Crusting-over of channels by oating lithoclasts, welded together (left) and by lateral
shelf accretion and consecutive closure (right; after Kempe, 2012b, modied).
520 Z. SAWŁOWICZ
channels, where they originally formed (Sauro et al., 2020).
Various rheological models have attempted to explain crust
formation in lava ows and lava tube formation (Dragoni
et al., 1995; Cashman et al., 2006; Valerio et al., 2011;
Filippucci et al., 2011). Near the eruption site, when the
lava surface temperature is high, the crust is thin and frag-
mented. With cooling, the fragments thicken and merge into
a continuous shell (Dragoni et al., 1995). The amount of
crust coverage is mainly controlled by the channel curvature
and width, narrow channels have a greater coverage than
wide ones (Valerio et al., 2011).
Speleothems and mineralogy
Mineral speleothems in lava caves and karst caves show
many similarities (Kempe, 2013; see also comparison in
Hill and Forti, 1997). However, many of the minerals of the
former are known only from lava caves (e.g., Etna Caves;
Forti, 2000).
There are both primary forms, consisting of the minerals
that make up tholeiitic basalt (rock speleothems or lavac-
icles), and secondary forms (mineral speleothems, sensu
Kempe, 2013; e.g., calcium carbonates, gypsum, opal, mi-
rabilite, tenardite, and vanadate phases; Forti, 2005; Hon
et al., 2009; Guimbretièr et al., 2014). Kempe (2013, table
1) elegantly compared the morphology of mineral and rock
speleothems. These two types result from different process-
es. Rock speleothems form in a very short time through the
ow of molten material , whereas mineral speleothems form
over long time scales through minute additions from solu-
tion (Kempe, 2013).
Among lava (rock) speleothems are tubular stalactites,
stalagmites, columns, soda straws, and corraloids, ow-
stones, helictites, barnacle-like stretched lava, runner, run-
ner channels, and lava blisters or squeeze-ups. Lava sta-
lagmites can exceed 3 m in height and a lava column in
a Korean lava tube cave is 7.6 m high (Hong, 1992).
According to Allred and Allred (1998), interstitial u-
id is expelled from lava as a result of retrograde boiling.
Stalactites are the most common rock speleothems. Kempe
(2013) distinguished several classes, differing in mode of
formation: 1) an extrusion of small amounts of melt from
the roof at regular distances; 2) a quick lowering of the lava
level, drawing down residual melt sheets from the ceiling;
3) the extruded residual melt rst forms drops and erratic
extrusions and nally forms a cylinder, drawn down be-
cause of the weight of the “pigtail” at the end; 4) a repeated
dipping of the pulsating lava ow; 5) spattering (Bosted and
Bosted, 2009); and 6) the cascading of lava down through
ceiling holes. Rock stalagmites also can be divided into sev-
eral morphological classes (Kempe, 2013): 1) agglutinated,
small and similar-sized drops of lava and broken fragments
of cylindrical stalactites; 2) larger spatter; and 3) fused, larg-
er amounts of lava, cascading down from upper passages or
through pukas from the surface.
Cave minerals in volcanic environments and their modes
of formation are described in the excellent overview by Forti
(2005). Lava cave minerals constitute up to 40% of the sec-
ondary chemical deposits found in all the caves of the world
and 35% of them are restricted to volcanic environments.
Processes, mechanisms, temperature ranges and related
chemical deposits are summarized in table 1 of Forti (2005).
Two mechanisms are exclusive to volcanic environments. In
the early stages, processes are practically controlled by the
temperature of the cave atmosphere. When the lava walls
cool, the chemical composition and the morphology of spe-
leothems change (Forti, 2005). A list of minerals restricted
to volcanic environments can be found in table 2 of Forti
(2005).
The chemical composition of secondary minerals found
in lava caves is diverse. A number of sulphate, chloride and
uoride minerals are formed, both in and around active lava
tubes. Hon et al. (2009) gave an excellent description of
these primary forms. Gases emitted from the lava in the
tubes react with the surrounding atmosphere and tube walls
and form both sublimates and precipitates. The spatial and
temperature zoning of these forms is interesting. Inside
the glowing tubes at temperatures >1000 °C, subhedral
anhydrite, glauberite and magnesioferrite are formed.
Cu-bearing Na2SO4 and KNaSO4 cover the walls direct-
ly outside the glow zone. Their lower temperature poly-
morphs, tenardite and afthitalite, are formed at temperatures
<300 o C in subsurface fumaroles. At temperatures of 100 to
400 °C, anhydrite and native sulphur are formed in the va-
cuoles. Surface and near-surface sulphatars form a mineral
complex of acid hydrated Mg-Fe-Al-Na sulphates (locally
uorides are also present). When the cooling lava comes
into contact with acid gases, gypsum, ralstonite, opal and
iron chlorides and hydroxides are formed. The drying of the
lava tube leads to the collapse of the transformation zones
and the formation of precipitates at 30–60 °C, dominated by
Na-Mg-K sulphates. After the tube cools down to the tem-
perature of the surrounding environment, these highly solu-
ble sulphates are removed by meteoric waters and gypsum
is formed in their place.
Minerals in the same lava tube can differ, depending on
the location. In basaltic caves at the Craters of the Moon
National Monument (USA) McHenry (2009) found that
most mineral coatings on the walls and ceilings were cal-
cite or silica-dominated, whereas mounds of Na-sulphate
and Na-carbonate precipitates were present on the oors.
The morphology, the occurrence and the numeric density
of several lava speleothems depend on which section of the
lava tube they formed in and the morphological diversity of
the different sections of the tube (Gadanyi, 2010).
Comparison of the chemical composition of the lava sta-
lactites (frozen lava drops) and the roof of the Etna lava
tube showed their high degree of similarity, with simulta-
neous large differences in the composition and texture of
plagioclases (Lanzafame and Ferlito, 2014). The oatation
of megacrysts (plagioclase laths) towards the top of a lava
tube was observed in the Snake River Plain Basalts, USA
(Shervais et al., 2005) and in the Khedrai Dam lava channel
(Deccan Volcanic Province; Sen et al., 2012).
Processes of oxidation are common and often very inten-
sive during the rst stages of lava tube formation. Oxidation
marks (oxidized olivine phenocrysts, ferruginous clinopy-
roxene and large amounts of hematite) are visible, both in
the rocks around the lava tubes and in the tubes themselves
(Atkinson et al., 1975).
521A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
Secondary minerals result from various chemical and
physical processes inside a lava tube. Many of them are
similar to those in karst caves, but some are not. Large
speleothems (up to 3 m long) with complex mineralogy
(mainly sodium carbonate) have been described from
a cave in carbonatites as resulting from the interaction of
endogenous condensates and meteoric waters (McFarlane
et al., 2004). Chemtob and Rossman (2014) described
opaque surface coatings, composed of amorphous silica
and Fe-Ti oxides. These coatings were the product of in-
teraction of the basaltic surface with volcanically derived,
acidic uids. Secondary minerals form within the host
rock and may seal the primary porosity of the lava (Kempe
et al., 2003). These fragile forms can be easily destroyed,
by natural and human forces. Guimbretière et al. (2014)
studied secondary minerals (from thenardite to vanadates
phases) in the lava tubes from a locally hot, recent vol-
canic ow of the Piton de la Fournaise volcano (Réunion)
and found that environmental conditions of the lava tube
evolved very quickly during three months and all the spe-
leothems disappeared.
A number of secondary speleothem types (e.g., moonmilk
and vermiculations) are formed through the action of microor-
ganisms or processes related to organic remains. Soft moon-
milk-type carbonate deposits were found in Cueva del Viento
(Tenerife, the Canary Islands; Gradziński and Jach, 2001) and
recently were studied extensively in the Show Caves on the
Galapagos Islands (Ecuador; Miller et al., 2020).
The presence of a high silica content in the basaltic walls
and/or sediments of volcanic caves is especially impor-
tant. The dispersed remains of lamentous microorganisms
were found on the coral-like formations in the Chilean Ana
Heva lava cave, composed of amorphous material, contain-
ing magnesium and silica (Miller et al., 2014). Kashima
et al. (1987) described speleothems in the caves in Japan,
consisting mainly of the skeletons of diatoms, alternating
with layers of clay and detrital material, cemented by silica.
De los Rios et al. (2011), examining the ochreous spele-
othems in a lava tube on the island of Terceira (Azores),
found bacterial structures in them and suggested that bac-
teria, through their metabolic activity, not only precipitate
ferrihydrite, but may also, through nucleation, contribute to
passive precipitation of minerals. Secondary mineral depos-
its in the lava caves are related to the biogenic mineralization
of bones and guano deposits. Forti et al. (2004) described
19 such minerals from lava in Saudi Arabia. Three of them
are extremely rare organic compounds strictly, related to the
combustion of guano.
In some lava caves, ice occurs the whole year round (e.g.,
Mauna Loa Icecave, Hawaii – see Kempe and Ketz-Kempe,
1979, or Bat Cave, New Mexico – see Crumpler and Aubele,
2001; Parmenter, 2018). A specic shape of lava cave (a col-
lapsed entrance in the upper section and deeper, descending,
sinuous passages) and a high-altitude location (not neces-
sary) may form a cold air trap (see Perşoiu and Onac, 2019).
These caves may contain so-called cryogenic minerals.
In two ice caves on the Mauna Loa volcano (Hawaii),
Teehera et al. (2018) found multi-phase deposits consisting
mainly of secondary amorphous silica, cryptocrystalline
calcite, and gypsum.
Water and lava caves
Lava caves are generally dry, but in some cases the pres-
ence of internal sediments evidences secondary water ow
(Gradziński and Jach, 2001, and references therein). On
Rapa Nui, Paulo (2009) observed that the silty inlling of
the lava caves is easily removed by waves, resulting in the
exposure of lava corridors, mostly at the coast; the recent
ones are in the wave range and the older ones high on the
cliffs. In 2004, Edmonds and Gerlach (2006) observed that
Kilauea lava was emerging from tubes on the lava delta
and owing into the sea as several continuous streams of
lava. Such ows generally ow into the sea passively but
explosive activity occurs, when the sea ows into under-
ground lava tubes (Mattox and Mangan, 1997). Some lava
cave systems, such as Lanzarote, include both dry and sub-
merged passages (e.g., Wilkens et al., 2009). In the case of
the Corona cave, it is assumed that it formed under subaerial
conditions and was later ooded during subsequent post-gla-
cial sea level rise (Wilkens et al., 2009, after Carracedo et
al., 2003). It is noteworthy that diving or snorkelling in wa-
ter-ooded lava caves is becoming popular, like geothermal
snorkelling in the Leitharendi lava cave on Iceland.
Lava tubes may be important in groundwater transport
and storage, forming a complex of ssured and conduit aq-
uifers within lava ows (for a comparison with karst aqui-
fers see Kiernan and Middleton, 2005).
Habitats
Living creatures of all sizes can be found in the majority
of caves, although only some of them live in lava caves.
Lava caves are used as shelters for various bigger mammals,
for example in Saudi Arabia, hyenas, wolves and foxes can
be found in lava caves (Forti et al., 2004). Rodents, birds,
and bats are common in entrances, skylights, and passages.
Carpets of moss develop near entrances and below skylights
in the lava tube caves. Together with thin roots from trees,
growing above the passages and often extending into the
cave, they are an excellent environment to host cave-adapt-
ed communities of troglobites (spiders, insects, craysh, sal-
amanders, and sh), fungi, and microbes. Spiders are espe-
cially common and some of them are without eyes (Gertsch,
1973). Over 100 invertebrate species have evolved in the
Hawaiian lava tubes, through a reduction in or loss of char-
acteristics (e.g., Bouseld and Howarth, 1976). Chapman
(1985) studied Hawaiian lava caves and found that most are
inhabited periodically, but some of them, with a favourable
microclimate, may become the main place of residence for
certain organisms. The main energy sources in Hawaiian
lava tubes are plant roots, especially Ohia-lehua, slimes de-
posited by organically rich, percolating ground water and
accidentals, which are those animals that blunder in and die
(Howarth, 1978). Different organisms are common at differ-
ent locations. For example, diplurans (hexapods) are present
in many lava tubes of the northwestern United States but are
poorly represented in volcanic caves elsewhere in the world
(Ferguson, 1992). In the submerged parts of lava caves, a va-
riety of aquatic fauna may develop, for example, remipede
crustaceans and polychaete worms (Wilkens et al., 2009).
522 Z. SAWŁOWICZ
Volcanic caves are lled with colourful microbial mats
on the walls and ceilings (e.g., Garcia et al., 2009; Moya et
al., 2009). Spores, coccoid, diatoms, and lamentous cells,
many with hair-like or knobby extensions, were some of
the microbial structures observed in biolms called “lava
wall slime”. Two types are common, snoottites (jelly-like
icicles hanging from the ceiling and walls of a cave) and
biovermicultions (various patterns of dots, lines, or net-
works, resembling dendrites or hieroglyphs on the walls of
a cave). Microbiological studies of lava caves are becoming
especially important in the context of detection of life in the
subsurface of extraterrestrial bodies (Northup et al., 2011).
Microbial communities in lava caves range from hard to
soft and from mineral deposits to the microbial mats that
line cave walls. Multi-coloured microbial mats and inor-
ganic secondary mineral deposits host a wide variety of
microorganisms (Northup et al., 2011). On the other hand,
the white and yellow microbial mats of the Azores and
Hawaii do not show much morphological differentiation
(Hathaway et al., 2014). Variations in local deposit param-
eters probably govern the composition of microorganisms
in recent volcanic deposits (Gomez-Alvarez et al., 2007).
Diatoms, including new species, are quite common in lava
caves near their entrances, in areas illuminated by natural
light (Rushforth et al., 1984; Lowe et al., 2013). It is inter-
esting to note that Navicula thurstonensis was found in the
Thurston Lava Tube (Hawaii), also in articially illuminat-
ed sections (Rushforth et al., 1984)
Lava caves can have a potential as sources of novel micro-
bial species and bioactive compounds, especially because
Actinobacteria (and Proteobacteria) usually predominate in
a lava cave environment (Cheeptham et al., 2013; Riquelme
et al., 2015; Lavoie et al., 2017). Interestingly, unique mi-
crobial diversity, distinct from other environments, includ-
ing cave environments, has been found in Hawaiian ice
caves (Teehera et al., 2018). Mineralized microbialites are
found not only deep in the darkness, but also grow on the
ceilings and walls in the photic zone of several open caves
in Hawaiian basalts, where fresh water seeps out of the rock
(Léveillé et al., 2000).
Man and mineral resources in lava caves
Lava caves have been used by man for many functions.
In Hawaii, lava caves (usually those that could be entered
through local ceiling collapses), especially in the near por-
tion of the opening, were used as temporary or permanent
shelters. Longer caves were places of refuge during wars
(Sinoto, 1992). Kempe et al. (1993, 2009) noted various
kinds of fortications in some caves. Radiocarbon dating
of charcoal supports the opinion that lava caves were used
by the rst inhabitants of the Hawaiian Islands (Allred et
al., 1999; Kempe et al., 2009). Lava caves were also used
as burial or religious sites (La Plante, 1992; Sinoto, 1992)
and some important cultural materials still exist in many
of them. Extensive studies of Polish speleologists and ar-
chaeologists in the lava caves on Easter Island (Rapa Nui)
proved that use of these caves by humans was very diversi-
ed and was changing with time (Sobczyk, 2009). They be-
came established as ceremonial objects; tombs; comfortable
night shelters; during inter-clan conicts, they were shelters
giving protection against enemies, occasionally with cam-
ouaged entrances. They served as natural water reservoirs
and the sites of arable land (manavai), where even today
fruit trees grow.
Caves are common places of occurrence of bat guano.
Such deposits occur mostly in limestone karst caves, but
lava caves are not excluded, for example in Saudi Arabia
(Forti et al., 2004) and Australia. There is commercial min-
ing of guano as fertilizer in Kenya (Simmons, 1998) and the
USA (Crumpler and Aubele, 2001; Parmenter, 2018).
Environmental pollution and the development of tourism
endanger lava cave systems, which are extremely sensitive
to external inuences. Halliday (2003) pointed out that
surface pollutants that ow into caves or are deliberately
dumped there threaten drinking water supplies, their ecosys-
tems and cultural artifacts. Discharges into lava caves may
put potable water reservoirs at risk of contamination. Where
the lava pipes have collapsed, small reservoirs of stagnant
water are formed, being available to local people (Kiernan
et al., 2003).
Lava tubes beyond the Earth
Lava caves also are widely distributed in volcanic elds
on planetary surfaces beyond the Earth (Fig. 5). The forma-
tion of Hadley Rille on Moon (Apollo 15 mission) through
a lava channel/tube mechanism was proposed already in
1988 by Spudis et al. (1988); for the Moon see also e.g.,
Greeley (1971) and Coombs and Hawke (1992). The fa-
mous Labyrinthus Noctis-Valles Marineris system on Mars
was proposed by Leone (2014) as a network of lava tubes.
Sinuous collapse chains and skylights in lunar and Martian
volcanic regions often have been interpreted as collapsed
lava tubes (Fig. 5B; e.g., Keszthelyi et al., 2008; Sauro et al.,
2020). Lava tubes have been proposed to occur also on
Fig. 5. Lunar lava tubes formations. A. Sinuous chain of col-
lapse pits transitioning into a continuous uncollapsed segment of
a lunar lava tube (copied from: http://www.nasa.gov/ mission_
pages/LRO/ multimedia/lroimages/ lroc-20110217-chain.html;
author – NASA/GSFC/Arizona State University). B. A 100 m
deep Lunar pit crater (Mare Tranquillitatis) – possible access to
a lava tube (copied from: http://photojournal.jpl.nasa.gov/ catalog/
PIA13518; author – NASA/GSFC/Arizona State University).
523A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
other planets and some natural satellites: Venus (Byrnes and
Crown, 2002), Mercury, Titan (Bleacher et al., 2015), and Io
(Crown et al., 1992; Keszthelyi et al., 2001). Their existence
is indicated mainly by images taken of vertical holes “sky-
lights” (Fig. 4A) by the LRO and SELENE spacecraft and
by gravity data from the GRAIL Mission (http://www.nasa.
gov/; Haruyama et al., 2009; Modiriasari et al., 2018). More
than 300 of these potential cave entrances have been iden-
tied on the Moon (Wagner and Robinson, 2019) and more
than 1,000 on Mars (Cushing, 2019). Interestingly, holes
have been discovered on the surface of Mars by American
middle school students on the basis of NASA’s HiRISE pho-
tos (http://asunews.asu.edu/20100617_skylight). It should
be noted that not all collapse structures, “skylights” or crater
pits must be related to lava tubes. Visual similarities can lead
us astray. Kempe (2017) showed deep hypogene sinkholes in
Arabia, which are strikingly similar to the holes on the Arsia
Mons volcano, on Mars. He suggested that the latter could
be associated with permafrost collapse sinks. Therefore,
simple visual interpretations should be assessed with cau-
tion. Extraterrestrial lava tubes have enormous dimensions,
being 1 to 3 orders of magnitude more voluminous than the
terrestrial analogues (Sauro et al., 2020). The GRAIL data
indicated that lava tubes can be 1–2 km wide and several
hundred kilometres long (Modiriasari et al., 2018). Zhao
et al. (2017) used CTX (Context Camera) and HiRISE
(High Resolution Imaging Science Experiment) images and
DTM (digital terrain model) derived from them to identify
the geomorphology of sinuous ridges with a lava-tube ori-
gin in Tharsis (Mars). Their lengths are estimated as varying
between ~14 and ~740 km and most of them occur on slopes
<0.3°. GRAIL observations and modelling show that lava
tubes even 1 km wide are likely to exist and remain stable
(Theinat et al., 2020). Sam et al. (2020) studied unmanned
aerial vehicle (UAV)-derived images of the Icelandic vol-
canic-aeolian environment and ssure volcanoes and found
a number of small caves and openings. They suggest that
similar openings could lead to vast subterranean hollow
spaces on Mars. S. Kempe (pers. comm., 2020) contests this
suggestion, considering the polar shifts of Mars and the as-
sociated dust covers of former ice caps. Dust should have
clogged any of these over billions of years.
Some researchers regard lava tubes as important means
of lava transportation beyond the Earth. They could have
facilitated magma transportation over the relatively low top-
ographic slopes and be important in the formation of long
lava ows. They are formed at low lava viscosity, relative-
ly low local ow rate, and sustained magma supply during
a long period (Schinella et al., 2011; Zhao et al., 2017 and
references therein). The formation processes of extrater-
restrial lava tubes may have varied and could have been
complex. Sauro et al. (2020) suggested that ination and
overcrusting processes, similar to those on the Earth, were
active on Mars, while deep ination and thermal entrench-
ment were the predominant mechanisms of emplacement on
the Moon. Branching channel networks on Mars could have
resulted from initial ow thickening, followed by the partial
drainage of preferred lava pathways (Bleacher et al., 2015).
Subsurface life on extraterrestrial bodies can be evalu-
ated on the basis of analogous subsurface environments on
Earth. Growing interest in the exploration of extraterrestri-
al planets and moons is justied by various expectations:
1) understanding of the formation of the Earth and other
planets; 2) building future human bases, sheltered against
hazards, such as meteorite impacts, temperature uctua-
tion, and seismic activity (Haruyama et al., 2009; Perkins,
2020). A reasonable overburden (greater than 6–8 m) will
reduce the radiation, due to high-energy particles of cosmic
rays (GCR) down to an “Earth-normal” background (Hong
et al., 2014; Turner and Kunkel, 2017); 3) potential sites
for the search for extraterrestrial organisms and nding
biogenic/organic compounds (Léveillé and Datta, 2010).
Lava tubes may contain groundwater or water ice deposits
and provide habitable environments, both past and present
(Grin et al., 1998; Williams et al., 2010; Schulze-Makuch
et al., 2015).
KAZUMURA CAVE, BIG ISLAND, HAWAII
THE LONGEST LAVA CAVE
IN THE WORLD
Kazumura Cave, located approximately 20 km south of
Hilo (Puna District), on the Big Island (Hawaii; Fig. 6), is
the longest lava cave in the world (65.5 km; Shick, 2012;
Gulden, 2021). Kazumura Cave is located on the northeast-
ern slope of Kilauea, a currently active volcano, stretch-
ing almost to the sea from the caldera. The host rocks are
tholeiitic basalt of the Ail ̒a ̒au lava ows, which spread
from the 1.5-km-long Kilauea Iki Crater (Fig. 6B), situated
east of Kilauea Caldera (Holcomb, 1987). This eruption is
considered the longest eruption of Kilauea in memory, with
lava covering an area of about 430 km2. Studies of Ail ̒a ̒au
basalt showed that the temperature drop in lava over
a 39-km section was only 4 °C. In contrast, the temperature
in the cave rises gradually from Kilauea (15 °C) to the coast
(22 °C; Allred and Allred, 1997). Greeley (1987) estimat-
ed that 58 % of the lava ows on Kilauea are likely to be
fed by lava tubes. Within the Ail ̒a ̒au Lava Field, on both
sides of Kazumura Cave, there are several other large lava
tubes and their systems, constituting one primordial sys-
tem (Halliday, 1994). The Kazumura, Ke’ala and Ainahou
caves, all on Kilauea, are good examples of single-trunk-
ed systems (Allred et al., 1997; Kempe, 2002). Kazumura
Cave also is an example of the intersection of different lava
ows. Lava of the Kazumura Flow intruded into the upper
and lower ends of the previously formed Keala tube in the
Ail ̒a ̒au Flow Field (Kempe, 1999).
The cave descends down the volcano from an elevation
of 1,130 m near the summit to 28 m at its lower end, giv-
ing a depth of 1,102 m for the lava cave. The depth below
the ground surface does not exceed 20 m (Allred and Allred,
1997). The average slope of the cave is 1.90–1.75° with
the upper sections of the cave being steeper and the lower
ones less steep (Halliday, 1994; Allred and Allred, 1997).
The formation of the cave and its host rocks is estimated as
taking place 350–500 years ago (Holcomb, 1987).
The best source of information on Kazumura Cave, its
morphology and development is the paper by Allred and
Allred (1997). A large amount of affordable information
524 Z. SAWŁOWICZ
on lava caves, based on extensive knowledge of Kazumura
Cave, also can be found in the book by Shick (2012), the
guide to this cave.
The Kazumura Cave Atlas lists 101 entrances, all on pri-
vate property. Most of the openings (maximum height about
3 m and width about 8 m; Fig. 7) leading to subterranean
passages result from the collapse of the roof. The corridors
have a maximum size of 21 m wide and 18 m high (Allred
and Allred, 1997). However, their cross-sectional areas are
different in different areas of the cave (Halliday, 1994).
They also vary at different levels. In upper levels, they are
likely to be wider and exhibit more uneven oors and walls
than that of the lowest and last active level (Allred and
Allred, 1997). Much of Kazumura Cave began as braided
networks, which evolved into a master tube. Thermal ero-
sion increased with the turbulence, caused by the steeper
slopes. Reinsulation of the lava stream created multi-level
development in spacious, downcut passages, especially be-
low the entrances (Allred and Allred, 1997). The oors of
passages usually have a ropy appearance. A ̒a lava, some-
times observed on the oor of the passages, results from the
cooling of the terminal ow, which increased the viscosity
of the lava and led to the disruption of the owing lava to
form clinker (S. Kempe, pers. comm., 2020). Rafted lava
blocks in the frozen residual ow are observed locally.
Many structures, common in world-wide lava caves, can
be studied in Kazumura Cave, such as: lava falls (Fig. 8A),
lava plunge pools (Fig. 9B), meanders, loops, multi-level
passages, windows, stacked and offset balconies, bridges,
sealed-off windows forming cupolas, injections, backcut-
ting, eddy current (Fig. 9A), collapses, lava explosions,
oaters, and others (Allred and Allred, 1997; Shick, 2012).
In many places, accretionary linings (glazing) formed, ow-
ing to uctuating lava levels, and are detached partly or
have broken loose and allow detailed observations. Wall
surfaces are especially in cul-de-sacs, very rough and un-
even, popcorn-like, possibly owing to degassing (Allred and
Allred, 1997). Interesting features of Kazumura Cave are
black lava ows, which intruded the cave through several
entrances. On the basis of the glassy skin and unmatching
cracks, Allred and Allred (1997) suggested that these ows
entered the cave after it had cooled.
Fig. 6. Kazumura Cave. A. Big Island (Hawaii) with its volcanoes and main towns. B. Location of Kazumura Cave (frame in A).
Fig. 7. Kazumura cave. A. One of the exits from the cave. B. Tree roots in the cave, indicating short distance from the surface.
525A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
Fig. 8. Various features of Kazumura Cave. A. Lavafall. B. Two levels passages.
C. Broken bench (levee) with two gutters. D. Exfoliations of thin lava linings.
Various types of braiding are observed in different parts
of the cave. Numerous undercuts and steep walls are ob-
served locally, especially in the sharp bends of the corri-
dors (Allred and Allred, 1997). Overlying tubes and lava-
falls indicate that the cave was formed in several stages.
Lavafalls are especially important for the development
of Kazumura Cave. They are numerous, especially in the
upper sections (Fig. 8A; Halliday, 1994). 41 falls and cas-
cades (height from 0.9 to 13.7 m) are listed in table 3 of
Allred and Allred (1997). Mature lava falls may develop
undercutting and secondary widening, which resulted in
cross-sections of caves that are larger than original chan-
nels (Kempe, 1997). After the migration of falls multiple
levels and other accretion may form downstream (Allred
and Allred, 1997).
Different types of lava speleothems (lavacicles), both
on roofs and walls, can be observed: tubular and coni-
cal lava stalactites (Fig. 10B), triangular blades (knobs;
Fig. 10C), soda straws (Fig. 10A), small lava stalagmites
formed by fused individual drops of lava, and lava helictites
(Fig. 10D), stringy lava, stretched lava, corraloids, and
Pele’s hair (Pele is Hawaiian goddess of volcanoes and re).
Secondary mineral speleothems are not common.
Variations in colour observed on the surface of the rocks
in Kazumura Cave are spectacular, but nding an explana-
tion for them is not easy. Differences in composition, ox-
idation, microbes and cooling rate, all can be responsible.
Typical tholeiitic basalt lava is black, but with a high pyrox-
ene or olivine content becomes green. Successive lava lin-
ings and runners (Fig. 9C) also often have different colours,
indicating early changes in chemical, and perhaps miner-
alogical, composition, Various shades of red are usually re-
lated to oxidation. The iron in volcanic glass is oxidized to
ne hematite in the outside air, while the lava is still hot. In
the presence of water vapour, also goethite and limonite are
formed (Kempe, 2012a). Red lavas are often found around
skylights or other openings that bring fresh air into the tube.
Microbial mats (Fig. 9D) and vermiculations also reveal
various colours. White or yellowish crusts are composed of
secondary minerals.
526 Z. SAWŁOWICZ
Fig. 9. Various features of Kazumura Cave. A. Rim (former crust) of the plunged lava pool. B. Frozen boiling lava texture. Note a
miniature „volcano” in the middle. C. Lava runners (dribblets) on the wall. D. Microbial red-brown slime with well-visible laments on
the surface of the basalt wall.
Kazumura Cave is inhabited periodically by various
species (Chapman, 1985). Native cavernicolous animals
are predominantly arthropods. Ten troglobitic and sev-
en native troglophilic (facultative cavernicoles) species
where found (Howarth, 1978). Multi-coloured moulds
or fungus layers occur on walls and ceilings, commonly
along paths of the frequent contraction cracks (Allred and
Allred, 1997).
People have used caves, including Kazumura Cave,
since prehistoric times, especially its last 9-km stretch near
the ocean (Allred and Allred, 1997). Many of the entrances
and collapses and the locally thin roof allow pollution in
many parts of the cave, both by natural processes at the
surface and by anthropogenic inuences. Extreme vandal-
ism and destructive impacts have been observed over the
years (Allred and Allred, 1997); fortunately, human aware-
ness is growing and the situation is slowly improving.
Some parts of the cave are accessible with specialist
equipment and a local guide, even by non-speleologists. It
goes without saying that visitors to lava caves in advance
should be made familiar with the information on appro-
priate behaviour in these caves and their preservation (see
Shick, 2012). In 1994, Halliday asked several questions
about the speleogenesis of Kazumura Cave. Many of them
still are not answered and should provide a challenge for
the future.
CONCLUSIONS
Lava tubes (pyroducts) form in volcanic ows and are
found in many volcanic regions of the world. Their distri-
bution and forms are described and their signicance for
the extention of volcanic ows is denoted. Thermal and
mechanical erosion are important factors in their forma-
tion. Different ways of pyroducts formation are discussed,
together with important parameters like temperature, vis-
cosity, and lava ow rate in active lava tubes. Primary lava
speleothems are different from those in karst caves and built
of different minerals. Methods of lava tube mapping and
lava temperature assessment in the Earth and beyond are
presented.
Habitats of lava caves, from bacterial to human, and their
mineral resources are shortly discussed. Lava caves may be
potential locations for life forms and future bases for space
exploration.
Basic features of lava tubes are illustrated with refer-
ence to the longest lava cave in the world, Kazumura Cave
(Hawaii).
527A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
Acknowledgements
A big mahalo goes out to all, who helped to improve this manu-
script: Harry Shick, who guided me through Kazumura Cave and
patiently answered my unlimited supply of questions; Brian Popp
and Peter Bosted for general and editorial comments; Jan Urban,
who read and commented on the manuscript; and nally my wife,
Alina, for unlimited patience during my endless photography of
Hawaiian naked, black stones. Editorial comments from Michał
Gradziński and Frank Simpson as well as the help of Waldemar
Obcowski (artwork) are appreciated. Special thanks go to Stephan
Kempe, whose detailed comments and criticisms helped me to
avoid many pitfalls.
REFERENCES
Allred, K. & Allred, C., 1997. Development and morphology of
Kazumura Cave, Hawaii. Journal of Cave and Karst Studies,
59: 67–80.
Allred, K. & Allred, C., 1998. Tubular lava stalactites and other
related segregations. Journal of Cave and Karst Studies, 60:
131–140.
Allred, K., Allred, C. & Richards, R., 1997. Kazumura Cave Atlas,
Island of Hawai‘i. Special Publication Hawai‘i Speleological
Survey, National Speleological Society, Huntsville, AL,
81 pp.
Allred, K., Kempe, S. & Halliday, W. R., 1999. Kenneth P. Emory
and “Herbert C. Shipman Cave”: a long-standing puzzle
solved. Pacic Studies, 22: 77–92.
Al-Malabeh, A. & Kempe, S., 2012. Hashemite University
Cave, Jordan. In: Al-Malabeh A. (ed.), Proceedings of the
15th International Symposium on Vulcanospeleology, 15–22
March, 2012. The Hashemite University, Zarka, Jordan,
pp. 43–48.
Antol, J., 2005. A new vehicle for planetary surface explora-
tion: The Mars Tumbleweed. In: 1st Space Exploration
Conference: Continuing the Voyage of Discovery.
30 January-1 February, 2005. Orlando, USA. American
Institute for Aeronautics and Astronautics, 2005–2520.
https://arc.aiaa.org/doi/10.2514/6.2005-2520 [10.02.2021; 1 p.]
Atkinson, A., Grifn, T. J. & Stephenson, P. J., 1975. A major
lava tube system from Undaro Volcano, North Queensland.
Bulletin Volcanologique, 39: 266–293.
Bauer, I., Kempe, S. & Bosted, P., 2013. Kahuenaha Nui, Hawaii,
a cave developed in four different lava ows. In: Filippi,
M. & Bosák, P. (eds), Proceedings of the 16th International
Congress of Speleology. Vol. 3. Czech Speleological Society,
Brno, pp. 231–236.
Bella, P. & Gaál, L., 2013. Genetic types of non-solution caves.
In: Filippi, M. & Bosák, P. (eds), Proceedings of the
16th International Congress of Speleology. Vol. 3. Czech
Speleological Society, Brno, pp. 237–242.
Fig. 10. Lavacicles in Kazumura Cave. A. Sharktooth (foreground) and tubular stalactites (width about 1–2 cm) and soda straws (width
about 0.5 cm; background). B. Conical stalactites (length about 5–10 cm). C. Accreted knobs (ns/blades), resulted probably from eddy
currents. D. Helictites (width about 0.5–1 cm).
528 Z. SAWŁOWICZ
Belousov, A. & Belousova, M., 2018. Dynamics and viscosi-
ty of ̒a ̒a and pāhoehoe lava ows of the 2012–2013 erup-
tion of Tolbachik volcano, Kamchatka (Russia). Bulletin of
Volcanology, 80: 1–23.
Bernardi, M. I., Bertotto, G. W., Ponce, A. D. Orihashi, Y.
& Sumino, H., 2019. Volcanology and ination structures
of an extensive basaltic lava ow in the Payenia Volcanic
Province, extra-Andean back arc of Argentina. Andean
Geology, 46: 279–299.
Bleacher, J. E., Hamilton, C. W., Scheidt, S. P., Garry, W. B., de
Wet, A., Whelley, P. & Williams, D. A., 2015. No erosion
needed: development of streamlined islands during lava
channel construction. In: 46th Lunar and Planetary Science
Conference, The Woodlands, Texas, March 16–20,
2015. p. 2182 https://www.hou.usra.edu/meetings/lpsc2015/
pdf/2182.pdf [10.02.2021; 2pp.]
Bosted, A. & Bosted, P., 2009. Exploration of Manu Nui Lava
Tube. Newsletter Hawai‘i Speleological Survey of the
National Speleological Society, 26: 3–13.
Bouseld, E. L. & Howarth, F. G., 1976. The cavernicolous fauna
of Hawaiian lava tubes 8. Terrestrial Amphipoda (Talitridae),
including a new genus and species with notes on its biology.
Pacic Insects, 17: 144–154
Bozzo, E., Coltelli, M., Merlanti, L. S. F. & Tabacco, I., 1994.
Geoelectromagnetic survey on the lava tube of the 1991–1993
Etna eruption. Acta Vulcanologica, 4: 125–133.
Budetta, G. & Del Negro, C., 1995. Magnetic eld changes on
lava ow to detect lava tubes. Journal of Volcanology and
Geothermal Research, 65: 237–248.
Bunnell, D., 2008. Caves of Fire: Inside America’s Lava Tubes.
National Speleological Society, Huntsville, 124 pp.
Byrnes, J. M. & Crown, D. A., 2001. Relationships between pāhoe-
hoe surface units, topography, and lava tubes at Mauna Ulu,
Kilauea Volcano, Hawaii. Journal of Geophysical Research,
Solid Earth, 106 (B2): 2139–2152.
Byrnes, J. M. & Crown, D. A., 2002. Morphology, stratigraphy,
and surface roughness properties of Venusian lava ow elds.
Journal of Geophysical Research, Planets, 107(E10), 5079:
19-1–19-22. doi:10.1029/2001JE001828
Calvari, S. & Pinkerton, H., 1998. Formation of lava tubes and
extensive ow eld during the 1991–1993 eruption of Mount
Etna. Journal of Geophysical Research, Solid Earth, 103
(B11): 27291–27302.
Calvari, S. & Pinkerton, H., 1999. Lava tube morphology on Etna
and mechanisms evidence on lava ow emplacement. Journal
of Volcanology and Geothermal Research, 90: 263–280.
Carracedo, J. C., Singer, B., Jicha, B., Guillou, H., Rodríguez
Badiola, E., Meco, J., Pérez Torrado, F. J., Gimeno, D.,
Socorro, S. & Lainez, A., 2003. La erupción y el tubo volcáni-
co del Volcán Corona (Lanzarote, Islas Canarias). Estudios
Geológicos, 59: 277–302.
Chapman, P. R. J., 1985. Are the cavernicoles found in Hawaiian
lava tubes just visiting. Proceedings of the University of
Bristol Spelaeological Society, 17: 175–182.
Chappaz, L., Sood, R., Melosh, H. & Howell, K., 2014. Buried emp-
ty lava tube detection with GRAIL data. In: Conference and
Exposition, 4–7 August 2014, San Diego, CA. The American
Institute of Aeronautics and Astronautics, Inc. 20 pp., https://
arc.aiaa.org/doi/10.2514/6.2014-4371. [10.02.2021] https://
doi.org/10.2514/6.2014-4371
Cashman, K. V., Kerr, R. C. & Grifths, R. W., 2006. A laboratory
model of surface crust formation and disruption on lava ows
through non-uniform channels. Bulletin of Volcanology, 68:
753–770.
Cashman, K., Pinkerton, H. & Stephenson, J., 1998. Introduction
to special section: Long lava ows. Journal of Geophysical
Research, Solid Earth, 103 (B11): 27281–2289.
Cheeptham, N., Sadoway, T., Rule, D., Watson, K., Moote, P.,
Soliman, L. C., Azad, N., Donkor, K. K. & Horne, D., 2013.
Cure from the cave: volcanic cave actinomycetes and their po-
tential in drug discovery. International Journal of Speleology,
42: 35–47.
Chemtob, S. M. & Rossman, G. R., 2014. Timescales and mecha-
nisms of formation of amorphous silica coatings on fresh ba-
salts at Kilauea Volcano, Hawai’i. Journal of Volcanology and
Geothermal Research, 286: 41–54.
Coan, T., 1844. Journey to Mauna Loa, Letter of March 15, 1843.
Missionary Herald, 40 (Feb.): 44–47.
Coombs, C. R. & Hawke, B. R., 1992. A search for intact lava tubes
on the Moon: Possible lunar base habitats. In: Mendell, W. W.
(ed.), The Second Conference on Lunar Bases and Space
Activities of the 21st Century. NASA Conference Publication,
3166, Vol. 1. Houston, pp. 219–229.
Coombs, C. R., Taylor, G. J. & Rowland, S. K., 1995. The forma-
tion and evolution of lava tubes. In: Abstracts of the Lunar
and Planetary Science Conference, 26: 279–280. http://
adsabs.harvard.edu/full/1995LPI....26..279C [10.02.2021]
Crown, D. A., Greeley, R., Craddock, R. A. & Schaber, G. G., 1992.
Geologic Map of Io. U.S. Geological Survey Miscellaneous
Investigations Series Map I-2209, 1:15,000,000. Reston, VA,
USA.
Crown, D. A, & Ramsey, M. S., 2017. Morphologic and thermo-
physical characteristics of lava ows southwest of Arsia Mons,
Mars. Journal of Volcanology and Geothermal Research, 342:
13–28.
Crumpler, L. S. & Aubele, J. C., 2001. Volcanoes of New Mexico:
an abbreviated guide for non-specialists. In: Crumpler, L.
S. & Lucas, S. G. (eds), Volcanology in New Mexico. New
Mexico Museum of Natural History and Science Bulletin,
18: 5–15.
Cushing, G. E., 2019. Mars Global Cave Candidate Catalog
(MGC3). USGS, Science-Base Catalog. https://www.sci-
encebase.gov/catalog/item/5bd36eb1e4b0b3fc5ce51783
[4.02.2021].
Cushing, G. E., Okubo, C. H. & Titus, T. N., 2015. Atypical pit cra-
ters on Mars: New insights from THEMIS, CTX, and HiRISE
observations. Journal of Geophysical Research:Planets, 120:
1023–1043.
de los Ríos, A., Bustillo, M. A., Ascaso, C. & Carvalho, M. D. R.,
2011. Bioconstructions in ochreous speleothems from lava
tubes on Terceira Island (Azores). Sedimentary Geology, 236:
117–128.
Diniega, S., Smrekar, S. E., Anderson, S. & Stofan, E. R., 2013.
The inuence of temperature-dependent viscosity on lava
ow dynamics. Journal of Geophysical Research: Earth
Surface, 118: 1516–1532,
Dragoni, M., Piombo, A. & Tallarico, A., 1995. A model for
the formation of lava tubes by roong over a channel.
Journal of Geophysical Research, Solid Earth, 100 (B5):
8435–8447.
529A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
Dragoni, M. & Santini, S., 2007. Lava ow in tubes with ellipti-
cal cross sections. Journal of Volcanology and Geothermal
Research, 160: 239–248.
Duraiswami, R. A., Bondre, N. R. & Dole, G., 2004. Possible
lava tube system in a hummocky lava ow at Daund, west-
ern Deccan Volcanic Province, India. Proceedings of Indian
Academy of Science (Earth Planetary Sciences), 113:
819–829.
Eberhard, R. & Sharples, C., 2013. Appropriate terminology
for karst-like phenomena: the problem with ‘pseudokarst’.
International Journal of Speleology, 42: 109–113.
Edmonds, M. & Gerlach, T. M., 2006. The airborne lava-seawa-
ter interaction plume at Kīlauea Volcano, Hawaiʻi. Earth and
Planetary Science Letters, 244: 83–96.
Ferguson, L. M., 1992. Diplura of lava tube caves. In: Rea, G. T.
(ed.), Proceeding of the 6th International Symposium on
Vulcanospeleology, August 1991, Hilo, Hawaii. National
Speleological Society, Huntsville, AL, pp. 281–284.
Filippucci, M., Tallarico, A. & Dragoni, M., 2011. Conditions for
crust and tube formation in lava ows with power-law rheolo-
gy. Bollettino di Geosica Teorica ed Applicata, 52: 309–319.
Flynn, L. & Mouginis-Mark, P., 1994. Temperature of an active
lava channel from spectral measurements, Kilauea Volcano,
Hawaii. Bulletin of Volcanology, 56: 297–301.
Fornari, D. J., 1986. Submarine lava tubes and channels. Bulletin
of Volcanology, 48: 291–298.
Forti, P., 2000. Minerogenetic mechanisms and cave minerals in
the volcanic caves of Mt. Etna (Sicily, Italy). Mitteilungen
Verband Deutschen Höhlen-und-Karstforschung, 46: 37–41.
Forti, P., 2005. Genetic processes of cave minerals in volcanic
environments: An overview. Journal of Cave and Karst
Studies, 67: 3–13.
Forti, P., Galli, E., Rossi, A., Pint, J. & Pint, S., 2004. Ghar al
Hibashi lava tube: the richest site in Saudi Arabia for cave
minerals. Acta Carsologica, 33: 189–205.
Gadanyi, P., 2010. Formation, Types and Morphology of Basalt
Lava Caves. Unpublished Ph.D. Thesis, University of Pécs,
Pécs, 19 pp.
Gallant, E., Deng, F., Connor, C. B., Dixon, T. H., Xie, S., Saballos,
J. A., Gutiérrez, C., Myhre, D., Connor, L., Zayac, J.,
LaFemina, P., Charbonnier, S., Richardson, J., Malservisi, R.
& Thompson, G., 2020. Deep and rapid thermo-mechanical
erosion by a small-volume lava ow. Earth and Planetary
Science Letters, 537, 116163. [8 pp.]
Garcia, M. G., Moya, M., Spilde, M. N., Stone, F. D. & Northup,
D. E., 2009. Discovering new diversity in Hawaiian lava
tube microbial mats. In: White, W. B. (ed.), Proceedings
of the 15th International Congress of Speleology19–26 July
2009, Kerville, Texas, USA. National Speleological Society,
pp. 364–369.
Gertsch, W. J., 1973. The cavernicolous fauna of Hawaiian lava
tubes, 3. Araneae (spiders). Pacic Insects, 15: 163–180.
Giacomini, L., Massironi, M., Martellato, E., Pasquare, G.,
Firgeri, A. & Cremonese, G., 2009. Inated ows on Daedalia
Planums (Mars)? Clues from a comparative analysis with
the Payen volcanic complex (Argentina). Planetary Space
Science, 57: 556–570.
Glaze, L. S. & Baloga, S. M., 2015. Simulation of cooling and
pressure effects on inated pahoehoelava ows. Journal of
Geophysical Research, Solid Earth, 121: 38–47.
Gomez-Alvarez, V., King, G. M. & Nusslein, K., 2007.
Comparative bacterial diversity in recent Hawaiian volcanic
deposits of different ages. FEMS Microbiology and Ecology,
60: 60–73.
Gradziński, M. & Jach, R., 2004. Lava tube caves – generals.
Przegląd Geologiczny, 49: 1191–1196. [In Polish, with
English summary.]
Greeley, R., 1971. Observations of actively forming lava tubes and
associated structures, Hawaii’. Modern Geology, 2: 207–223.
Greeley, R., 1987. The role of lava tubes in Hawaiian volca-
noes. U.S. Geological Survey Professional Papers, 1350:
1589–1602.
Greeley, R., Fagents, S. A., Harris, R. S., Kadel, S. D., Williams,
D. A. & Guest, J. E., 1998. Erosion by owing lava: Field
evidence. Journal of Geophysical Research, Solid Earth, 103
(B11): 27325–27345.
Grin, E., Cabrol, N. & McKay, C., 1998. Caves in the Martian
regolith and their signicance for exobiology exploration.
In: 29th Lunar and Planetary Science Conference, Houston,
TX, Abstract #1012. https://www.lpi.usra.edu/meetings/
LPSC98/pdf/1012.pdf [10.02.2021; 2 pp.].
Guimbretière, G., Canizarès, A., Finizola, A., Delcher, E.,
Raimboux, N., Veron, E., Simon, P., Devouard, B. & Bertil,
A., 2014. Raman study of secondary minerals in a recent
lava tube. In: 11th GeoRaman International Conference,
June 15–19, 2014, St. Louis, Missouri, USA. https://
www.hou.usra.edu/meetings/georaman2014/pdf/5057.pdf
[10.02.2021; 2 pp.].
Gulden, B., 2021. World’s Longest Lava Tubes. http://caverbob.
com/ lava.htm [05.02.2021].
Halliday, W. R., 1994. Recent vulcanospeleological progress in
Hawaii. In: Oromi, P. (ed.), 7th International Symposium on
Vulcanospeleology, Santa Cruz de La Palma, Canary Islands,
November 1994. Federatión Española de Espeleología and
Federatión Canaria de Espeleología, pp. 51–58.
Halliday, W. R., 1998. Hollow volcanic tumulus caves of Kilauea
Caldera, Hawaii County, Hawaii. International Journal of
Speleology, 27B: 95–105.
Halliday, W. R., 2002. What is a lava tube? AMCS Bulletin 19 /
SMES Boletín, 7: 48–56.
Halliday, W. R., 2003. Raw sewage and solid waste dumps in
lava tube caves of Hawaii Island. Journal of Cave and Karst
Studies, 65: 68–75.
Halliday, W. R., 2004. Volcanic caves. In: Gunn, J. (ed.),
Encyclopedia of Caves and Karst Science. Fitzroy Dearborn,
New York, pp. 761–764.
Harris, A., 2006. Heat loss models for active lava channels and tubes:
Controls on ow cooling and length. In: Höskuldsson, A.,
Wilson, C. J., Sigmundsson, F., Larsen, G., Sigurdsson, H.,
Rowland, S., Self, S., Sparks, S. & Thordarson, T. (eds),
A George P. L. Walker Symposium on Advances in Volcanology,
Reykholt, Borgarfjordur, W-Iceland, 12–17 June 2006.
International Association of Volcanology and Chemistry of
the Earth’s Interior, p. 14.
Harris, A. J. L., Blake, S., Rothery, D. & Stevens, N., 1997.
A chronology of the 1991 to 1993 Mount Etna eruption
using advanced very high-resolution radiometer data:
implications for real-time thermal volcano monitoring.
Journal of Geophysical Research, Solid Earth, 102 (B4):
7985–8003.
530 Z. SAWŁOWICZ
Harris, A. J. L., Dehn, J. & Calvari, S., 2007. Lava effusion rate
denition and measurement: a review. Bulletin of Volca-
nology, 70: 1–22.
Harris, A. J. L. & Rowland, S. K., 2009. Effusion rate controls
on lava ow length and the role of heat loss: a review.
In: Thordarson, T., Self, S., Larsen, G., Rowland, S. K.
& Hoskuldsson, A. (eds), Studies in Volcanology:
The Legacy of George Walker. Special Publications of
IAVCEI, 2. Geological Society, London, pp. 33–51.
Harris, A. J. L., Rowland, S. K., Villeneuve, N. & Thordarson, T.,
2017. Pāhoehoe, ‘a‘a, and block lava: an illustrated history
of the nomenclature. Bulletin of Volcanology, 79: 76–34.
Haruyama, J., Hioki, K., Shirao, M., Morota, T., Hiesinger, H.,
Van Der Bogert, C. H., Miyamoto, H., Iwasaki, A., Yokota,
Y., Ohtake, M., Matsunaga, T., Hara, S., Nakanotani, S.
& Pieters, C. M., 2009. Possible lunar lava tube skylight
observed by SELENE cameras. Geophysical Research
Letters, 36, L21206. [5 pp.]
Hathaway, J. J. M, Garcia, M. G., Balasch, M. M., Spilde, M. N.,
Stone, F. D., Dapkevicius, M., De Lurdes N. E., Amorim,
I. R., Gabriel, R., Borges, P. A. V. & Northup, D. E., 2014.
Comparison of bacterial diversity in Azorean and Hawai’ian
Lava Cave Microbial Mats. Geomicrobiology Journal, 31:
205–220.
Hill, C. & Forti, P., 1997. Cave Minerals of the World. National
Speleological Society, Huntsville, AL, 463 pp.
Holcomb, R., 1987. Eruptive history and long-term behavior of
Kilauea volcano, in Volcanism in Hawai‘i. In: Decker, R.,
Wright, T. & Stauffer, P. (eds), Volcanism in Hawaii. Papers
to Commemorate the 75th Anniversary of the Founding of
the Hawaiian Volcano Observatory.U.S. Geological Survey
Professional Paper, 1350: 261–350.
Hon, K., Bove, D. J., Lee, L. & Thornber, C., 2009, The origin and
zonation of sublimates and precipitates in active Hawaiian
lava tubes. Geological Society of America Abstracts with
Programs, 41 (7): 193.
Hon, K., Kauahikaua, J., Denlinger, R. & Mackay, K., 1994.
Emplacement and ination of pāhoehoe sheet ows: obser-
vations and measurements of active lava ows on Kilauea
Volcano, Hawaii. Geological Society of America Bulletin,
106: 351–370.
Hong, I.-K., Yi, Y. & Kim, E., 2014. Lunar pit craters presumed
to be the entrances of lava caves by analogy to the Earth
lava tube pits. Journal of Astronomy and Space Sciences, 31:
131–140.
Hong, S. H., 1992. Caves in Cheju Island, Korea. In: Rea, G. T.
(ed.), Proceeding of the 6th International Symposium on
Vulcanospeleology: Hilo, Hawaii, August 1991. National
Speleological Society, Huntsville, AL, pp. 168–169.
Howarth, F. G., 1978. Hawaii IBP synthesis: 4. The Hawaiian
lava tube ecosystem. In: Smith C. W. (ed.), Proceedings of
the Second Conference in Natural Sciences Hawaii Volcanoes
National Park; 1978, June 1–3; Honolulu. University of
Hawaii, Manoa, pp. 155–164.
Hulme, G., 1973. Turbulent lava ow and the formation of lunar
sinuous rilles. Modern Geology, 4: 107–117.
Hulme, G., 1982. A review of lava ow processes related to
the formation of lunar sinuous rilles. Surveys in Geophysics,
5: 245–279.
Huppert, H. E., Sparks, R. S. J., Turner, J. S. & Arndt, N. T., 1984.
Emplacement and cooling of komatiites lavas. Nature, 309:
19–22.
Hurwitz, D. M., Fassett, C. I., Head, J. W. & Wilson, L., 2010.
Formation of an eroded lava channel within an Elysium
Planitia impact crater: distinguishing between a mechanical
and thermal origin. Icarus, 210: 626–634.
Jaggar, T. A., 1919. Monthly Bulletin of the Hawaiian Volcano
Observatory, 7: 5.
Kalita, H., Morad, S., Ravindran, A. & Thangavelautham, J., 2018.
Path planning and navigation inside off-world lava tubes and
caves. In: 2018 IEEE/ION Position, Location and Navigation
Symposium (PLANS), Monterey, CA, April 2018. Monterey,
CA, pp. 1311–1318. doi:10.1109/PLANS.2018.8373521
https://arxiv.org/ftp/arxiv/papers/1803/1803.02818.pdf
[10.02.2021]
Kashima, N., Irie, T. & Kinoshita, N., 1987. Diatom, contributors
of coralloid speleothems, from Togawa-Sakaidani-do cave in
Miyazaki prefecture, Central Kyushu, Japan. International
Journal of Speleology, 16: 95–100.
Kauahikaua, J., Cashman, K. V., Mattox, T. N., Heliker, C. C., Hon,
K. A., Mangan, M. T. & Thornber, C. R., 1998. Observations
on basaltic lava streams in tubes from Kilauea volcano, island
of Hawai’i. Journal of Geophysical Research, Solid Earth,
103 (B11): 27303–27323.
Kauahikaua, J., Denlinger, R., Foster, J. & Keszthelyi, L., 1993.
Lava delta instability: Is it mass-wasting or is it triggered by
lava owing through tubes. Eos, Transactions, 74: 616.
Kauahikaua, J., Moulds, T. N. & Hon, K., 1990. Observations of
lava tube formation in Kalapana, Hawai’i. Eos, Transactions,
71: 1711.
Kauahikaua, J., Sherrod, D. R., Cashman, K. V., Heliker, C., Hon,
K., Mattox, T. N. & Johnson, J. A., 2003. Hawaiian Lava-
Flow Dynamics During the Pu‘u ‘Ö‘ö-Küpaianaha Eruption:
A Tale of Two Decades. U.S. Geological Survey Professional
Paper, 1676: 63–97.
Kempe, S., 1997. Lavafalls: a major factor for the enlargement
of lava tubes of the Ai-la`au Shield phase, Kilauea, Hawaii.
In: Jeannine, P-Y. (ed.), Proceedings of the 12th International
Congress of Speleology, Swiss Speleological Society, 10–17
September, 1997, La Chaux-de-Fonds, Switzerland. Speleo
Projects, Basel, Switzerland, pp. 445–448.
Kempe, S., 1999. Mapping lava ows by surveying lava tubes ex-
ample: Ail ̒a ̒au/Keauhou ows, Kilauea /Hawaii. In: Barone,
N., Bonaccorso, R. & Licitra, G. (eds), Proceedings of
the 9th International Symposium on Vulcanospeleology.
September 11–19, 1999, Catania, Italy. Centro Speleologico
Etneo, p. 131.
Kempe, S., 2002. Lavaröhren (pyroducts) auf Hawai‘i und ihre
Genese. In: Rosendahl, W. & Hoppe, A. (eds), Angewandte
Geowissenschaften in Darmstadt. Schriftenreihe der
Deutschen Geologischen Gesellschaft, 15: 109–127.
Kempe, S., 2009. Principles of pyroduct lava tunnel formation.
In: White, W. B. (ed.), Proceedings of the 15th International
Congress of Speleology, 19–26 July 2009, Kerrville, Texas,
USA. National Speleological Society, pp. 668–674.
Kempe, S., 2012a. Volcanic rock caves. In: White, W. B. & Culver, D. C.
(eds), Encyclopedia of Caves. Academic Press/Elsevier,
Amsterdam, pp. 865–873.
531A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
Kempe, S., 2012b. Lava caves, types and development.
In: Al-Malabeh, A. (ed.), Proceedings of 15th International
Symposium on Vulcanospeleology, 15–22 March, 2012.
The Hashemite University, Zarka, Jordan, pp. 49–56.
Kempe, S., 2013. Morphology of speleothems in primary
(lava-) and secondary caves. In: Shroder, J. & Frumkin, A.
(eds), Treatise on Geomorphology. Karst Geomorphology.
Academic Press, San Diego, CA, pp. 267–285.
Kempe, S., 2017. What if the “Seven Sisters” are not volcanic?
A look at deep hypogene sinkholes in Arabia. In: Moore,
K. & White, S. (eds), Proceedings of the 17th International
Speleology Congress, 22–30 July, 2017, Sydney, NSW
Australia. Australian Speleological Federation Inc., Sydney,
pp. 371–374.
Kempe, S., 2019. Volcanic rock caves. In: White, W. B., Culver, D. C.
& Pipan, T. (eds), Encyclopedia of Caves. Academic Press/
Elsevier, Amsterdam, pp. 1118–1127.
Kempe, S. & Al-Malabeh, A., 2005. Newly discovered lava tun-
nels of the Al-Shaam plateau basalts. Geophysical Research
Abstracts, 7, 03204. [3 pp.]
Kempe, S., Bauer, I., Bosted, P., Coons, D. & Elhard, R., 2010.
Inationary versus crusted-over roofs of pyroducts (lava
tunnels). In: Middleton, G. J. (ed.), Proceedings of the 14th
International Symposium on Vulcanospeleology, August 2010,
Undara Volcanic National Park, Queensland, Australia.
Published by the Organizing Committee, pp. 93–101.
Kempe, S., Bauer, I. & Henschel, H.-V., 2003. P ̒a ̒auhau Civil
Defense Cave on Mauna Kea, Hawai’i – A lava tube modied
by water erosion. Journal of Cave and Karst Studies, 65: 76–85.
Kempe, S., Henschel, H. V., Shick, H. & Hansen, B., 2009.
Archaeology and 14C dates of the Kamakalepo/Waipouli/
Stonehenge area, Nahalehu, Hawai‘i. In: White, W. B. (ed.),
Proceedings of the 15th International Congress of Speleology,
Kerrville, Texas, July 19–26, 2009. National Speleological
Society, pp. 682–689.
Kempe, S. & Ketz-Kempe, C., 1979. Fire and ice atop Hawaii.
National Speleological Society News, 37: 185–188.
Kempe, S., Ketz-Kempe, C., Halliday, W. R. & Werner, M. S.,
1993. The Cave of refuge, Hakuma Horst, Kalapana, Puna
District, Hawaii. Pacic Studies, 16: 133–142.
Kempe, S., Middleton, G., Addison, A., Toulkeridis, T. & Hoese,
G., 2018. Genesis of pyroducts of the Galápagos Islands,
Ecuador. In: Proceedings of the 18th International Symposium
on Vulcanospeleology, 21–28 July, 2018, Lava Beds National
Monument, California, USA. http://www.vulcanospeleology.
org/sym18/Proceedings/Kempe_I.pdf [10.02.2021; 2 pp.]
Kempe, S. & Werner, M. S., 2003. The Kuka‘iau Cave, Mauna
Kea, Hawai‘i, created by water erosion, a new Hawaiian cave
type. Journal of Cave and Karst Studies, 65: 53–67.
Kerr, R. C., 2001. Thermal erosion by laminar lava ow. Journal
of Geophysical Research, Solid Earth, 106: 26453–26465.
Kerr, R. C., 2009. Thermal erosion of felsic ground by the laminar
ow of a basaltic lava, with application to the Cave Basalt,
Mount St. Helens, Washington. Journal of Geophysical
Research, Solid Earth, 114 (B9), B09204. [14 pp.] https://doi.
org/10.1029/2009JB006430
Keszthelyi, L., 1995. A preliminary thermal budget for lava tubes
on the Earth and planets. Journal of Geophysical Research,
Solid Earth, 100 (B10): 20411–20420.
Keszthelyi, L. & Self, S., 1998. Some physical require-
ments for the emplacement of long basaltic lava ows.
Journal of Geophysical Research, Solid Earth,103 (B11):
27447–27464.
Keszthelyi, L., Jaeger, W., McEwen, A., Tornabene, L.,
Beyer, R. A., Dundas, C. & Milazzo, M., 2008. High
Resolution Imaging Science Experiment (HiRISE) imag-
es of volcanic terrains from the rst 6 months of the Mars
Reconnaissance Orbiter Primary Science Phase. Journal of
Geophysical Research, Planets, 13, E04005. [25 pp.] doi.
org/10.1029/2007JE002968
Keszthelyi, L., McEwen, A. S., Phillips, C. B., Milazzo, M.,
Geissler, P., Turtle, E. P., Radebaugh, J., Williams, D. A.,
Simonelli, D. P., Breneman, H. H., Klaasen, K. P., Levanas, G.
& Denk, T., 2001. Imaging of volcanic activity on Jupiter’s
moon Io by Galileo during the Galileo Europa Mission and
the Galileo Millennium Mission. Journal of Geophysical
Research, Planets, 106 (E12): 33025–33052.
Keszthelyi, L., Self, S. & Thordarson, Th., 1999. Application of
recent studies on the emplacement of basaltic lava ows to
the Deccan Traps. Memoirs of the Geological Survey of India,
43: 485–520.
Kiernan, K. & Middleton, G., 2005. Groundwater move-
ment and management in tube-fed lavas. In: Proceedings
of the 15th Australasian Conference on Cave and Karst
Management, 5–11 May, 2003, Chillagoe, North Queensland,
Australia. pp. 40–45. https://eprints.utas.edu.au/10104/1/
scan_11%5B1%5D.pdf [10.02.2021]
Kiernan, K., Wood, C. & Middleton, G., 2003. Aquifer structure
and contamination risk in lava ows: insights from Iceland
and Australia. Environmental Geology, 43: 852–865.
La Plante, M., 1992. Recently Discovered Hawaiian Religious
and Burial Caves. In: Rea, G. T. (ed.), Proceedings of the 6th
International Symposium on Vulcanospeleology, Hilo, HI,
August 1991. National Speleological Society, Huntsville, AL,
pp. 7–9.
Lanzafame, G. & Ferlito, C., 2014. Degassing driving crystalli-
zation of plagioclase phenocrysts in lava tube stalactites on
Mount Etna (Sicily, Italy). Lithos, 206: 338–347.
Larson, C. V., 1993. An Illustrated Glossary of Lava Tube Features.
Charlie and Jo Larson, Vancouver, Washington, 56 pp.
Lavoie, K. H., Winter, A. S., Read, K. J. H., Hughes, E. M.,
Spilde, M. N. & Northup, D. E., 2017. Comparison of bac-
terial communities from lava cave microbial mats to overly-
ing surface soils from Lava Beds National Monument, USA.
PLOS One, 12 (2), e0169339. [27 pp.]. doi:10.1371/journal.
pone.0169339
Leone, G., 2014. A network of lava tubes as the origin of Labyrinthus
Noctis and Valles Marineris on Mars. Volcanology and
Geothermal ResearchJournal of Volcanology and Geothermal
Research, 277: 1–8.
Léveillé, R. J. & Datta, S., 2010. Lava tubes and basaltic caves as
astrobiological targets on Earth and Mars: a review. Planetary
and Space Science, 58: 592–598.
Léveillé, R. J., Fyfe, W. S. & Longstaffe, F. J., 2000. Unusual sec-
ondary Ca-Mg-carbonate-kerolite deposits in basaltic caves,
Kauai, Hawaii. The Journal of Geology, 108: 613–621.
Lockwood, J. P. & Hazlett, R. W., 2010. Volcanoes, a Global
Perspective. John Wiley, Chichester, 624 pp.
532 Z. SAWŁOWICZ
Lowe, R. L., Kociolek, J. P. & Van De Vijver, B., 2013. Two new
Orthoseira species (Bacillariophyceae) from lava tubes on Île
Amsterdam and Big Island (Hawai΄i). Phytotaxa, 111: 39–52.
Mattox, T. N. & Mangan, M. T., 1997. Littoral hydrovolcanic
explosions; a case study of lava-seawater interaction at
Kīlauea Volcano. Journal of Volcanology and Geothermal
Research, 75: 1–17.
McFarlane, D. A., Lundberg, J. & Belton, F., 2004. An unusual
lava cave from Ol Doinyo Lengai, Tanzania. Journal of Cave
and Karst Studies, 66: 98–101.
McHale J. C., 2013. Lava Tube Modeling: A case Study of a Lava
Tube along a Shore Platform in Lavericks Bay, New Zealand.
http://frontiersabroad.com/wp-content/uploads/2014/03/
McHale_Lava-Tube-Modeling.pdf [1.12.2020; 22 pp.].
McHenry, L. J., 2009. Unusual sulphate cave mineral deposits at
craters of the Moon National Monument, Idaho: Potential
analogue for Meridiani Planum, Mars. In: 18th Annual
Wisconsin Space Conference, The Hubble and beyond,
14–15August, 2008. (Green Bay, Wisconsin). Wisconsin
Space Grant Consortium. https://www.researchgate.net/
publication/214103680_Unusual_sulfate_cave_mineral_de-
posits_at_Craters_of_the_Moon_National_Monument_
Idaho_Potential_analogue_for_Meridiani_Planum_Mars
[10.02.2021; 10 pp.]
Miller, A. Z., García-Sánchez, A. M., Coutinho, M. L., Costa
Pereira, M. F., Gázquez G., Calaforra, J. M., Forti, P.,
Martínez-Frías, J., Toulkeridis, T., Caldeira, A. T. & Saiz-
Jimenez, C., 2020. Colored microbial coatings in show caves
from the Galapagos Islands (Ecuador): First microbiological
approach. Coatings, 10, 1134. [15 pp.]. doi:10.3390/coatings
10111134
Miller, A. Z., Pereira, M. F. C., Calaforra, J. M., Forti, P., Dionísio,
A. & Saiz-Jimenez, C., 2014. Siliceous speleothems and
associated microbe-mineral interactions from Ana Heva Lava
Tube in Easter Island (Chile). Geomicrobiology Journal, 31:
236–245.
Miyamoto, H., Haruyama, J., Kobayashi, T., Suzuki, K., Okada, T.,
Nishibori, T., Showman, A. P., Lorenz, R., Mogi, K., Crown,
D. A., Rodriguez, J. A. P., Rokugawa, S., Tokunaga, T.
& Masumoto, M., 2005. Mapping the structure and depth of lava
tubes using ground penetrating radar. Geophysical Research
Letters, 32: L21316. [5 pp.] doi:10.1029/2005GL024159,
2005
Modiriasari, A., Theinat, A., Bobet, A., Melosh, H., Dyke,
S., Ramirez, J., Maghareh, A. & Gomez, D., 2018. Size
and structural stability assessment of lunar lava tubes. In:
49th Lunar Planetary Science Conference, March 19–23,
2018, The Woodlands, TX, 49, 2860. [2 pp] https://www.pur-
due.edu/reth/les/Papers/LPSC-Lava%20tube%20paper.pdf
Moya, M., Garcia, M. G., Spilde, M. N. & Northup, D. E., 2009.
Composition of bacterial mats in El Malpais, National
Monument, New Mexico, USA: comparison and contrasts
with bacterial communities in Hawai‘i lava tubes. In: White,
W. B. (ed.), Proceedings of the 15th International Congress
of Speleology, Kerrville, Texas, 19–26 July, 2009. National
Speleological Society, pp. 709–713.
Nádudvari, A., Abramowicz, A., Maniscalco, R. & Viccaro, M.,
2020. The estimation of lava ow temperatures using Landsat
Night-Time Images: Case studies from eruptions of Mt. Etna
and Stromboli (Sicily, Italy), Kilauea (Hawaii Island), and
Eyjafjallajökull and Holuhraun (Iceland). Remote Sensing,
12, 2537. [26 pp.]
Nelson, C. E., Jerram, D. A., Hobbs, R. W., Terrington, R.
& Kessler, H., 2011. Reconstructing ood basalt lava ows in
three dimensions using terrestrial laser scanning. Geosphere,
7: 87–96.
Northup, D. E., Melim, L. A., Spilde, M. N., Hathaway, J. J. M.,
Garcia, M. G., Moya, M., Stone, F. D., Boston, P. J.,
Dapkevicius, M. E. N. L. & Riquelme, C., 2011. Lava cave
microbial communities within mats and secondary miner-
al deposits: Implications for life detection on other planets.
Astrobiology, 11: 601–618.
Parmenter, D. S., 2018. Ice and Guano Deposits in El Malpais
Lava Tubes: Potential Paleoclimate Archives for the
Southwest United States. Graduate Theses and Dissertations.
https://scholarcommons.usf.edu/etd/8135. [1.12.2020; 89 pp].
Pasquarè, G., Bistacchi, A., Francalanci, L., Bertotto, G. W., Boari,
E., Massironi, M. & Rossotti, A., 2008. Very long pāhoehoe
inated basaltic lava ows in the Payenia volcanic province
(Mendoza and la Pampa, Argentina). Revista de la Asociación
Geológica Argentina, 63: 131–149.
Paulo, A., 2009. Geology of the Easter Island. In: Ciszewski,
A., Ryn, Z. J. & Szelerewicz, M. (eds), The Caves of Easter
Island. Underground World of Rapa Nui. AGH University of
Science and Technology, Kraków, Poland, pp. 74–78.
Pedersen, G. B. M., Höskuldsson, A., Dürig, T., Thordarson, T.,
Jonsdottir, I., Riishuus, M. S., Óskarsson, B. V., Dumont, S.,
Magnússon, E., Gudmundsson, M. T. & Sigmundsson, F.,
2017. Lava eld evolution and emplacement dynamics of
the 2014–2015 basaltic ssure eruption at Holuhraun, Iceland.
Journal of Volcanology and Geothermal Research, 340:
155–169.
Perkins, S., 2020. Core concept: Lava tubes may be havens for
ancient alien life and future human explorers. Proceedings of
the National Academy of Sciences, 117: 17461–17464.
Perşoiu, A. & Onac, B. P., 2019. Ice in caves. In: White, W. B.,
Culver, D. C. & Pipan, T. (eds), Encyclopedia of Caves.
Elsevier, Amsterdam, pp. 553–558.
Peterson, D. W. & Swanson, D. A., 1974. Observed formation
of lava tubes during 1970–71 at Kilauea Volcano, Hawaii.
Studies in Speleology, 2: 209–222.
Peterson, D. W. & Tilling, R. I., 1980. Transition of basaltic lava
from pāhoehoe to aa, Kilauea Volcano, Hawaii: Field observa-
tions and key factors. Journal of Volcanology and Geothermal
Research, 7: 271–293.
Peterson, D. W., Holcomb, R. T., Tilling, R. I. & Christiansen, R. L.,
1994. Development of lava tubes in the light of observa-
tions at Mauna Ulu, Kilauea Volcano, Hawaii. Bulletin of
Volcanology, 56: 343–360.
Pinkerton, H., James, M. & Jones, A., 2002. Surface tempera-
ture measurements of active lava ows on Kilauea volcano,
Hawai’i. Journal of Volcanology and Geothermal Research,
113: 159–176.
Ramalho, R. S., Quartau, R., Trenhaile, A. S., Mitchell, N. C.,
Woodroffe, C. D. & Avila, S. P., 2013. Coastal evolution on
volcanic oceanic islands: a complex interplay between vol-
canism, erosion, sedimentation, sea-level change and biogen-
ic production. Earth-Science Reviews, 127: 140–170.
Realmuto, V. J., Hon, K., Kahle, A. B., Abbott, E. A.,
& Pieri, D. C., 1992. Multispectral Thermal Infrared
533A SHORT REVIEW OF PYRODUCTS (LAVA TUBES)
Mapping of the 1 October 1988 Kupaianaha ow eld,
Kilauea Volcano, Hawaii. Bulletin of Volcanology, 55: 33–44.
Riker, J. M., Cashman, K. V., Kauahikaua, J. P. & Montierth, C. M.,
2009, The length of channelized lava ows: Insight from the
1859 eruption of Mauna Loa Volcano, Hawai‘i. Journal of
Volcanology and Geothermal Research, 183: 139–156.
Riquelme, C., Hathaway, J. J. M., Dapkevicius, M. L. N. E.,
Miller, A. Z., Kooser, A., Northup, D. E., Jurado, V.,
Fernandez, O., Saiz-Jimenez, C. & Cheeptham, N., 2015.
Actinobacterial diversity in volcanic caves and associated
geomicrobiological interactions. Frontiers in Microbiology, 6,
1342 [16 pp.] https://doi.org/10.3389/fmicb.2015.01342
Rogers, K. L., Repenning, C. A., Luiszer, F. G. & Benson, R. D.,
2000. Geologic history, stratigraphy, and paleontology of
SAM Cave, north-central New Mexico. New Mexico Geology,
22: 89–117.
Rushforth, S. R., Kaczmarska, I. & Johansen, J. R., 1984.
The subaerial diatom ora of Thurston Lava Tube, Hawaii.
Bacillaria, 7: 135–157
Sakimoto, S. E. H., Crisp, J. & Baloga, S. M., 1997. Eruption
constraints on tube-fed planetary lava ows. Journal
of Geophysical Research, Planets, 102 (E3): 6597–6614.
Sakimoto, S. E. H. & Zuber, M. T., 1998. Flow and convective
cooling in lava tubes. Journal of Geophysical Research,
Solid Earth, 103 (B11): 27465–27487.
Sam, L., Bhardwaj, A., Singh, S., Martin-Torres, F. J., Zorzano,
M-P. & Ramírez Luque, J. A., 2020. Small lava caves as pos-
sible exploratory targets on Mars: Analogies drawn from UAV
imaging of an Icelandic lava eld. Remote Sensing, 12, 1970.
[30 pp.] doi:10.3390/rs12121970
Sauro, F., Pozzobon, R., Massironi, M., De Berardinis, P., Santagata,
T. & De Waele. J., 2020. Lava tubes on Earth, Moon and Mars:
A review on their size and morphology revealed by com-
parative planetology. Earth-Science Reviews, 209, 103288.
[21 pp.] https://doi.org/10.1016/j.earscirev.2020.103288
Schinella, E., O’Neill, C. & Afonso, J. C., 2011. Processes form-
ing volcanic topography at Alta Regio, Venus. In: Cairns, I.
& Short, W. (eds), Proceedings of the 10th Australian Space
Science Conference, Brisbane, Australia. National Space
Society of Australia Ltd., Sydney, pp. 105–118.
Schulze-Makuch, D., Schulze-Makuch, A. & Houtkooper, J. M.,
2015. The Physical, chemical and physiological limits of life.
Life, 5: 1472–1486.
Sen, B., Sabale, A. B. & Sukumaran, P. V., 2012. Lava channel of
Khedrai Dam, northeast of Nasik in Western Deccan Volcanic
Province: Detailed morphology and evidences of channel
reactivation. Journal of Geological Society of India, 80:
314–328.
Shervais, J. W., Kauffman, J. D., Gillerman, V. S., Othberg, K.
L., Vetter, S. K., Hobson, V. R., Zarnetske, M., Cooke, M. F.,
Matthews, S, H. & Hanan, B. B., 2005. Basaltic volcanism
of the central and western Snake River Plain: A guide to eld
relations between Twin Falls and Mountain Home, Idaho. In:
Pederson, J. & Dehler, C. M. (eds), Interior Western United
States. Geological Society of America Field Guide 6, 26 pp.
Shick, H., 2012. Understanding Lava Tubes and Lava Caves.
Kazumura Cave Tours. Keaau, HI, USA. Trafford, Victoria,
British Columbia, 128 pp.
Siewert, J. & Ferlito, C., 2008. Mechanical erosion by owing
lava. Contemporary Physics, 49: 43–54.
Simons, J. W., 1998. Guano mining in Kenyan lava tunnel caves.
International Journal of Speleology, 27: 33–51.
Sinoto, J. H., 1992. Hawaiian use of lava tube caves and shelters.
In: Rea, G. T. (ed.), Proceedings of the 6th International
Symposium on Vulcanospeleology, August 1991, Hilo, HI,
USA. National Speleological Society, Huntsville, AL, pp. 3–6.
Sobczyk, M., 2009. Archaeological objects in the caves of Easter
Island. In: Ciszewski, A., Ryn, Z. J. & Szelerewicz, M. (eds),
The Caves of Easter Island. Underground World of Rapa
Nui. AGH University of Science and Technology, Kraków,
pp. 87–93.
Spampinato, L. Calvari, S., Harris, A. J. L. & Dehn, J., 2008.
Evolution of the Lava Flow Field by Daily Thermal and
Visible Airborne Surveys. https://www.earth-prints.org/bit-
stream/ 2122/4279/1/spampinato%20et%20al.%20%20AGU.
pdf [6.02.2021; 27 pp.]
Spudis, P. D., Swann, G. A. & Greeley, R., 1988. The formation of
Hadley Rille and implications for the geology of the Apollo
15 region. In: 18th Lunar and Planetary Science Conference,
16-20 March, 1987, Houston, TX, Proceedings A89-10851
01-91. Cambridge University Press/Lunar and Planetary
Institute, Cambridge, UK, pp. 243–254. http://adsabs.harvard.
edu/full/1988LPSC...18..243S [10.02.2021]
Teehera, K. B., Jungbluth, S. P., Onac, B. P., Acosta-Maeda, T. E.,
Hellebrand, E., Misra, A. K., Pitsch, A., Rappé, M. S., Smith,
S. M., Telus, M. & Schorghofer, N., 2018. Cryogenic minerals
in Hawaiian lava tubes: A geochemical and microbiological
exploration. Geomicrobiology Journal, 35: 227–241.
Theinat, A. K., Modiriasari, A., Bobet, A., Melosh, H. J., Dyke, S. J.,
Ramirez, J., Maghareh, A. & Gomez, D., 2020. Lunar lava
tubes: Morphology to structural stability. Icarus, 338: 113442.
[30 pp.] https://doi.org/10.1016/j.icarus.2019.113442
Tilling, R. I. & Peterson, D. W., 1993. Field observation of active
lava in Hawaii: some practical considerations. In: Kilburn, C.
& Luongo, G. (eds), Active Lavas: Monitoring and Modelling.
UCL Press, London, pp. 147–174.
Turner, R. E. & Kunkel, R., 2017. Radiation environment inside
a Lunar lava tube. In: 47th International Conference on
Environmental System (ICES), 16–20 July, 2017, Charleston NC.
ICES-2017-15. https://ttu-ir.tdl.org/bitstream/handle/ 2346/72863/
ICES_2017_ 15.pdf?sequence=1&the total depts=y [7 pp.]
Umino, S., Nonaka, M. & Kauahikaua, J., 2006. Emplacement
of subaerial pāhoehoe lava sheet ows into water: 1990
Kupaianaha ow of Kılauea volcano at Kaimu Bay, Hawaii.
Bulletin of Volcanology, 69: 125–139.
Valerio, A., Tallarico, A. & Dragoni, M., 2011. Effects of the cur-
vature of a lava channel on ow dynamics and crust forma-
tion. Geophysical Journal International, 187: 825–832.
Wagner, R. & Robinson, M., 2019. 3D modeling of Lunar pit walls
from stereo images. In: 50th Lunar and Planetary Science
Conference 2019, LPI Contrib. No. 2132 poster. https://
www.hou.usra.edu/meetings/lpsc2019/eposter/2138.pdf
[10.02.2021; 1 p.]
Waichel, B., Tratz, E. B., Pietrobelli, G. & Barbosa da Silva, W.,
2013. Lava tubes from the Paraná-Etendeka Continental Flood
Basalt Province: Morphology and importance to emplace-
ment models. Journal of South American Earth Sciences, 48:
255–261.
Wantim, M., Kervyn, M., Ernst, G., Marmol, M., Suh, C.
& Jacobs, P., 2013. Morpho-structure of the 1982 lava ow
534 Z. SAWŁOWICZ
eld at Mount Cameroon Volcano, West-Central Africa.
International Journal of Geosciences, 4: 564–583.
Whittaker, W., 2011. Technologies enabling exploration of sky-
lights, lava tubes and caves. NASA Innovative Advanced
Concepts (NIAC) Phase I. Astrobotic Technology,
Pittsburgh, Pa, 51 pp. https://www.nasa.gov/ pdf/
718393main_Whittaker_2011_PhI_Cave_Exploration.pdf
[1.12.2020;].
Whittington, A. G., Sehlke, A. & Morrison, A. A., 2020. Tubular
hells: new measurements of lunar magma rheology and
thermal properties applied to thermal erosion and lava tube
formation. In: 3rd International Planetary Caves 2020,
St. Antonio, TX (LPI Contrib. No. 2197). https://www.hou.
usra.edu/meetings/3rdcaves2020/pdf/1077.pdf [10.02.2021;
2 pp.]
Wilkens, H., Iliffe, T. M., Oromí, P., Martínez, A., Tysall, T. N.
& Koenemann, S., 2009. The Corona lava tube, Lanzarote:
geology, habitat diversity and biogeography. Marine
Biodiversity, 39: 155–167.
Williams, D. A., Kadel, S. D., Greeley, R., Lesher, C. M. & Clynne,
M. A., 2003. Erosion by owing lava: geochemical evidence
in the Cave Basalt, Mount St. Helens, Washington. Bulletin
of Volcanology, 66: 168–181.
Williams, D. A., Kerr, R. C. & Lesher, C. M., 1998. Emplacement
and erosion by Archean komatiite lava ows at Kambalda:
Revisited. Journal of Geophysical Research, Solid Earth, 103
(B11), 27533–27549.
Williams, D. A., Kerr, R. C. & Lesher, C. M., 1999. Thermal
and uid dynamics of komatiitic lavas associated with
magmatic Ni-Cu- (PGE) sulphide deposits. In: Keays, R. R.,
Lesher, C. M., Lightfoot, P. C. & Farrow, C. E. G. (eds),
Dynamic Processes in Magmatic Ore Deposits and Their
Application in Mineral Exploration. Geological Association
of Canada. Short Courses Notes, 13: 367–412.
Williams, K. E., McKay, C. P., Toon, O. B. & Head, J. W., 2010.
Do ice caves exist on Mars? Icarus, 209: 358–368.
Williams, K. E., Titus, T. N., Okubo, C. H. & Cushing, G. E.,
2017. Martian cave air-movement via Helmholtz reso-
nance. International Journal of Speleology, 46: 439–444.
Wise, C., 2014. Crack systems analysis of the McCartys Flow, New
Mexico, USA. Senior Capstone Projects, Paper 302. http://
digitalwindow.vassar.edu./senior_capstone/302. [30.01.2021;
52 pp.]
Witter, J. B. & Harris, A. J. L., 2007. Field measurements of
heat loss from skylights and lava tube systems. Journal
of Geophysical Research: Solid Earth, 112, B01203 [21 pp.].
doi: 10.1029/2005JB003800
Zhao, J., Huang, J., Kraft, M. D., Xiao, L. & Jiang, Y., 2017.
Ridge-like lava tube systems insoutheast Tharsis, Mars.
Geomorphology, 295: 831–839.
